I have this same problem and haven't been able to solve it... have you figured out a solution?
So far I've tried:
uninstalling and reinstalling the app (both regular and pro versions)
restarting the phone
restarting the mount
re-reading the az-gti directions
searching the internet (this was one of the few discussions on this issue!)
I'm wondering if our mounts are defective... or if this is a known bug that hasn't been fixed... or if it's some unique bug just between our phones and the app (I use a Samsung Galaxy S8+.... is that what you use?).