Unwanted auto-flatten

Hello guys,

this problem annoyed me for a while. I always draw with the brush tool and never use the auto-flatten option or (knowingly) any shortcut or button that would flatten my strokes. Yet randomly a couple of drawings end up being flattened making it impossible for me to cut lines with the cutter tool mouse gesture.
I wonder how that can happen? What could I have done accidentely to flatten these drawings? Is this some automatic optimization feature?

I would really appreciate any idea :slight_smile:

It happens when you use the smooth editor tool.

I’ve had this same issue numerous times recently, and I have never used the smooth editor tool. All I’m doing is laying a lot of strokes, then immediately switching to the cutter tool to clean it up. Part way through the clean-up, I realize the cutter has stopped working, and when I select my art, everything has been flattened. Could this happen during an auto-save point?