How can I fix Gboard hang after I use google dictation (long press on spacebar)? I'm trying to use Gboard dictation on my iPhone 6s+ running iOS 9.3.3.
Dictation pops up when I long-press on the spacebar and it takes dictation BUT - once it decides to switch back to the requesting app - either by timing out or my pressing on the color bars - the colored dots spin forever. 

If I switch manually to the other app the text is there.

Anyone know what's going on here? Can anyone else repro it? Is it unique to iOS 9.3.3?

I'm dev-knowledgable but not for iOS. Any tips on debugging this? Wish I could get a stack trace and know what system call Gboard is hanging on.
Xcode has a visual profiler and debugger called instruments. Once you r device with your Mac, you might be able to snoop on the error logs, system calls and such. You will be at the mercy of however much symbols and logging google enables. 

Better might be to seek support from the vendor of the app if Xcode is either not an option or not helpful once you try it. 

N-2 iOS version support might be scant from google, but it’s only your time to try and get support from them.