[glennmcg]

Please send me one of the csv and PDF files that is causing that for you. I've never seen that during my testing with the CSV files I've used. Do I just need to import multiple csv files in a row to see that problem? Or is it more prevalent with certain files?

Thanks,
Mike

How should I send the sample pair?  

Note that I already have 30,000 pieces pointing at almost 10,000 PDF files already in the database. 
These entries were created by me programmatically inserting into an empty MobileSheets DB file (just the entries that you get from a fresh install, or DB clear).

The hang occurs before I can hit the OK button. And the same files work if I kill the program and restart.

I spent some time trying to get a stack dump for you, but it seems I need to root my device first. 
I've also had hangs going into settings, and coming out with a similar dialog.

With no evidence to back it, it feels like a GC pause. (My java/kotlin programmer hat).