What version of FMGO are you using? What ios version is on the iPads?
You may need to update FMGo. You also might trying power cycling the device and removing FMGo and reinstalling.
ios: iOS 9.3.5
FM: Go_iPad 13.0.8
ios: iOS 10.0.2
FM: Go_iPad 13.0.9
Both iPads say the ios is up to date??
FM 14, let alone 13 is not compatible with iOS 10 -- at least according to a response by a TS person that I saw over in Report an Issue here.
any way to go back to ios 9?
FMGo is knowm to have a memory leak bug that cause crashes and as Philmodjunk has stated it not compatible, so I would suggest upgrading FMGo.
Going back to ios9 would require erasing your phone and restore a backup prior to the upgrade to ios10.
You can install FMGo 14 and or FMGo 15 and test. You can have all three versions installed at the same time.
I installed FMGo 15 and it works.
I was afraid I may have had upgrade the FM systems on the computers to FM15 as well. My client isn't ready for that yet (probably as long as you can still upgrade to the latest FM from FM13 he won't be).