(Mac), use option-o or select from the chord menu.
Because the different OS's have different coding requirements (hence three different apps) switching between them is sort of like shopping in a different supermarket, most everything is there, just in a different place.
Sort of like a (mostly) parallel universe.
for the Mac version, you can use option-o (lowercase letter o) for half diminished.
Also you can simply enter the letter name of the chord (e.g. Ab or E etc.) then click the arrow at the right end of the chord field for the menu of all the chord qualities the player will recognise.