hrm... I havent had any issue with formation audibles working, basically the rules on what it places there are the same.

for a Deep Pass, you need a 4 verts type play, sometimes you can get others in there Smash a common one, RnS plays are others.
for a Short Pass Quick Slants, Stick, Screens
for a PA pass, a PA pass or Option pass if you have a slants or stick play in short you can get a screen
for a Run it will take any run, but a Dive/inside run has first priority

You follow the rules and the formation audibles are pretty easy.