This is exactly what i did, but if the player is in air, it still double jumps if they press the left or right button.
Double jump is setup with a variable so If player is in air> Double jump is 0 > Touch > Set vector etc etc > set doublejump to 1
EDIT: I Tried it your way by setting double jump enabled on the platform behaviour,that worked however its not as smooth as my own made doublejump, it only doublejumps if player is falling.
Weird how this way does not work when I do the same but with a variable condition and instead of platform jump I set it to set vector, really strange.
Make a boolean variable for all buttons and say
If - is touching button = set button boolean /true
If - not touching button = set button boolean /false
And now you can say
If - on any touch & all button boolean /false = set jump