This happened for the first time. I think maybe something wrong with last update.
I exported timelapse of illustration and found out that first 60-70% of it is replaced with timelapse of different file that I painted before (!), so almost it’s all gone now. Check please, it somehow replace timelapse of one file with another. I don’t remember for sure, but I think these two files were opened at the same time. Maybe bug is something there. If needs to, I can share this bugged .artstudio file.