Thank you for the additional info - and that's a great suggestion! I'll see if I can get that implemented and uploaded in the next day or two :)
Ohhh I figured it out. It happens if a zero tile auto-clears a falsely flagged tile.
That is incredibly helpful - thank you so much for figuring out how to reproduce that!!
Thank you for trying to fix it, it's a really cool game.
Aw, I'm so glad you think so! And the issue should now be fixed - thank you again for all of your help, it is super appreciated :D