My issue step by step:
1 - open assembly
2 - open part from assembly
3 - flatten part
4 - close part file without saving
5 - now the assembly contains the part as flat pattern, and lots of mate errors
6 - rebuild assembly, still flat pattern and errors
7 - open part again, it is flat pattern
8 - unflatten part
9 - close part file without saving
10 - assembly is now back to original state
This is SW2017 and files not checked out of pdm vault (read only).
To me it is counter intuitive behavior when the assembly does not update to cancelled changes, especially when the files are read only. Is there a setting to fix this?