I tried to slice this spritesheet, settings columns to 10 and rows to 50, and it freezes:

LPC Fruit Trees

Thanks for the report and the test content, Girkov. I'm trying to replicate this issue using the LPC Fruit Trees content but the app doesn't freeze, I will try a few other large sprite sheets and if I can reproduce the error I will issue an update asap.

Thanks for reporting this, I've fixed the bug