Version

2.3.0

Operating system type + version

OS Name Microsoft Windows 10 Pro N
Version 10.0.19042 Build 19042

3D printer brand / version + firmware version (if known)

Prusa MK3S
Firmware is latest (~30/JAN/2021)

Behavior

Opened .3mf produced using 3DPrint option in Solidworks CAD.
FYI Just noticed (might be a factor?):

Windows Explorer preview shows Solidworks model, with SmartDimension
The re-edited one was SavedAs as a different .3DF filename...
And it previews as a PS-generated model image, without dimensions

Opened it in PrusaSlicer (no issues, no errors, before or after)
Set the surface to contact the bed (FYI: this took 20sec or more to display the white-shaded surfaces)
Also repositioned the model
Added modifier block (to alter infill)
Added two layer ranges, each with different infill
Don't think that the Save button was ever clicked... :(

Some time later... (no other issues encountered)...
Closed PrusaSlicer (Window Close button, top-right)
No warning message appeared (such as a warning to 'Save unsaved work?' )
Then, File/Open... Recent (opened last file)

Found 3DF the file had not been saved - manually, automatically, or when closing the app: positions, orientation, modifiers did not save.

• Steps needed to reproduce the problem
  See above. Problem occurred again (with just orientation altered): exiting the PS program ignores changes made.

• Expected Results
  I expected there to be a prompt to save the PS is exited/closed if there had been unsaved changes. Or if this was a 'crash', it should recover perhaps?

• Actual Results
  PrusaSlicer exited promptly without a prompt save changes.

Is this a new feature request?
NO

Project File (.3MF) where problem occurs

The attached 3DF file is generated using 3DPRINT option in Solidworks. No other issues found.

SofaFootREAR_V01a Solidworks output.zip