Cannot re-open a picture

[nucleardirk]

Hey!
I worked on a small collage on the iPhone 12 Pro.
After some days I wanted to rework again on the file but pixelmator said:

Can not open the file. Error 33.
after that error occured, the project was not on my device any more.
I have about 20 GB free space on the device so memory to save shouldn’t be an issue.

Also sometimes, closing a project causes that not all steps from my work were stored.
Looks like saving process might have issues.