I will deeply appreciate any piece of advice leading to solve the following mystery.
I have a SU file (the only one of these kinds of its behaviour in my life - attached-please-find under the link below) that behaves in a very strange manner.
Both in SU 2020 Pro and SU 2021 Pro (windows Pro 10 64 bit, 64 RAM, Nvidia RTX 5000 12 GB).
Whilst I save the file it reacts as well instantly after the save as undo the very last operation. Ex moving an object, changing tag visibility, etc.
The only way to fix it is to perform Cleanup (plugin) or via native SU utilities with checking the errors just before saving the file in question. No errors are found.
Some parts within the file come from Autocad. Perhaps there are some overlaps that I cannot identify.
I do thank you for any elucidation. It has been still workable but very annoying,
I tried your file on Mac without apparent problems.
The axes have been repositioned but they are not far from original axes position and the model is not far from axes origin and is not very large. So, I see no problems there.
I added a line then saved the model. The edge stayed in the model. I quoted SU then reopened the file, no problem. The added edge is still present so no problem.
The only change I noticed is that your downloaded file was around 52 Megs while, after saving, you file size dropped to about 32 Megs even if I didn’t do any purge. Then, I did a purge and saw no change.
I revealed hidden geometries and saw additional stuff that don’t look overly complex. However, the statistics reveal millions of edges and faces.
So far I have not experienced the unusual Undo that you describe.
I will let more experienced users chime in on that. Notice, that I am on Mac.