WBS failure - number sequence not always correct

It is possible because the WBS field is user editable although I don't know why a user would edit it as shown in your screen shot.

Is it possible the last user applied a sort and then saved? It doesn't explain the duplicate WBS numbers but it could explain the out-of-sequence WBS numbering.

I also run Project, via Parallels, on an iMac and the files users send to me for troubleshoot/questions are (I'm assuming) all from a Windows machine. I've never seen this type of anomaly so I doubt it has anything to do with Windows native versus Windows emulated.

Do the other users report any issues with the WBS? As far as fixing it, I would first make sure the file is not sorted or filtered. Then manually clean up all the WBS anomalies and save the file. You might consider also saving locally under a new name. If the file is then shared and comes back in WBS disarray, run the Compare Projects utility found under the Reports tab on the ribbon and see what changed.

John