Thinking about it when you say
do you mean that Ab minor does not appear on the list of scales in Scaler?
If you click on the ALL NOTES button and select G#/Ab as the root note
then click on G# on the G# minor scale
it will change to Ab
As I said above
That´s probably the reason. thanks for the input!
Wiki has an interesting note on when G#/ Ab are not tonally equivalent, and that is for tunings which are not 12TET (e.g. Meantone and Pythagorean)
Of course that didn’t make anyone’s day go better, and is certainly not worth using scarce brain-bytes to remember, so zzzzaaaappp G# = Ab
Not a theory expert here, but this is my take on it:
For single notes it makes sense to always have the sharp (#) and the flat (b) notation, because whether one you use depends on the context of the scale.
For scales though, maybe the reason is the circle of fifth and how we notate the flats and sharps in music notation?
As you can see there, only Gb/F# and D# / Eb can be stated either way as it can be included in both sharpened and flattened scales. A g# is already on the side of the circle where it’s always in a sharpened scale and in context of those it’s a g# and not an Ab note. Of course you could have 7 flats instead of 5 sharps (as the circle of fifth picture below hints at), but it’s more inconvenient.
But I don’t know if this makes sense. The circle of fifth is also kind of biased towards our western scales I think. Just an idea that came to my mind when reading the question.
I found that information bit interesting and funny. That’s the kind of (useless?) information your brain like to keep 
You are absolutely correct when you say
The circle of fifths is focussed on 12 tone western scales. There are many other tonal systems in music (some of which may be referred to as microtonal) such as Indian, Asian, etc. where the circle of fifths cannot be readily applied.
Even in western music based on 12 tone scales there are styles that do not follow the “rules”. IMHO the most common of these is atonal music, which may be used in film and television to establish the mood of a scene, e.g. creating tension etc.
Scaler, of course, offers many different scales but because most computer based DAWS and vstis (and hardware) are based producing music using western 12 tone scales then there is, I believe, an in-built bias towards it.
It is worth reading this free book on theory.
Of the soft synths I have used / evaluated, Omnisphere is (thus far) unique in supporting an extraordinary range of different tunings (including microtonal) which can even be applied at a patch level in a multi. 89 separate tunings are supported, which include a range of kalimba / mbira tunings. I’m sure there are others which do likewise.
I’ve never tried to use any of them …
The Surge XT vsti (an open source and therefore free semi modular, hybrid synthesizer) supports microtuning, but this is beyond my musical ability. It was originally a commercial product and there are a number of preset packs available for it.
As I understand it, each note in a scale (key) must be a unique letter, as in key of C (C, D, E, F, G, A, B - C), To build a minor scale on Ab (and using the relative major of B as a clearer example) you run into a problem looking at it as Ab because, in the case of it’s relative major Bb major (the easiest way to see this to start), the 3rd and 4th, and 7th and 1, does not give a unique letter (Eb, E - Bb, B). In order to spell out each degree of the scale the sharp/flat determination must be viewed as sharps in order to have a unique letter for each degree. B, C#, D#, E, F#, G#, A#, B. To use flats it would spell: B, Db, Eb, E, Gb, Ab, Bb, B which not only uses the same letter twice, it omits 2 letters. So in the case of: ‘is it G# or Ab?’, it’s G# - G#, A#, B, C#, D#, E, F# - G#.
Welcome to the forum @MusicGuy
I’ll let the seasoned theorists respond to this but my 2 cents is the Circle of Fifths is your friend here. It’s a great tool for memorising how many sharps and flats make up each scale. In your examples the relative major of G# minor (G♯, A♯, B, C♯, D♯, E, and F♯) is B major (B, C♯, D♯, E, F♯, G♯, and A♯). The same key in a major scale is usually referred to as Ab major (A♭, B♭, C, D♭, E♭, F, and G) with its relative minor being F minor (F, G, A♭, B♭, C, D♭, and E♭).
Hi @MusicGuy
I think you are making a simple, but understandable, error when you say
The relative major for Ab is not B maj, it is Cb maj. B maj and Cb maj are enharmonic (i.e. they use the same notes on the keyboard) but they are different scales.
This becomes more obvious when considering the natural minor scale: for Ab min the scale notes are Ab, Bb, Cb, Db, Eb, Fb, Gb. This scale is the Aeolian mode of Cb major (i.e. it is based on the 6th degree of the Cb maj scale and uses the notes from the Cb major scale).
To find the relative minor of a major scale simply take the 6th degree of the major scale and build a scale using the notes from the major scale, Conversely to find the relative major the the root note of the natural minor is the 6th note of its relative major.
Better still, use the Circle of Fifths as suggested by @davide. On the Circle of Fifths you will see that the relative major of Ab min is Cb maj if you select either the Harmonic Minor or Melodic Minor.
As an aside I believe that Cb maj is not used very often in music because the scores are relatively difficult to read when compared with B maj; the key signatures being 7 flats for Cb maj as opposed to 5 sharps for B maj). Terefor you are mor likely to find compositions in G# minor (relative major is B with 5 sharps in the key signature) rather than Ab minor with 7 flats).
Thanks, I should have been clearer by saying:
“To build a minor scale on Ab (and using the relative major of B as a clearer example of why G# minor is the proper naming, rather than Ab) you run into a problem looking at it as Ab because…etc.”
is wrong as B is not the relative major of Ab: the relative major of Ab is Cb (the 6th of Cb). So the sequence
is, I think, wrong as the scale is not the scale of B major, it is the scale of Cb major, and the scale notes are Cb, Db, Eb, Fb, Gb, Ab.
G# minor is the relative minor of B but it is not the same scale as Ab although the two scales are enharmonic.
Of course, in practical terms this only becomes important when scoring music and playing form the score IMHO.
ed66, I did not say Ab is the relative minor of Bb, G# is the relative minor. I was simply answering the question, why doesn’t software give you Ab minor as opposed to G# minor. Please start reading at the top with the original question and once you get to my post read it even slower, please. I was pointing out that all letters must be represented when spelling a scale and to call it Ab minor is incorrect because whether you want to view the relative major as B or Cb, you do not end up with all letters represented either way. You must call it G# minor, and view the relative major as B in order that all letters are spelled out when reviewing the degrees of the scale…
This is one of the situations where I am happy to don’t know music, so I can play plugins and select series of chords by ear, skipping all those complex (and scaring 
) calculations
