Unable to Open Document; We weren't able to restore the saved database to the model

I just updated to the latest version to take advantage of the new features; but it has busted a bunch of my report files.

Whenever I open a previously created report and save it (even with no changes what so ever) the file becomes unusable, with the error "Unable to Open Document We weren't able to restore th saved database to the model" thrown at launch.

The files were created with Power BI Desktop 2.39.4526.362 and my projects get corrupted when saving them using Power BI Desktop 2.40.4554.361

The projects work in the latest version until the file is saved and Power BI Desktop is closed, but any attempt to reopen the file will throw the error.

I have reverted to version 2.39.4526.362 and do not experience this issue any more, so I'll have to do my customer case with the older version (which is annoying since I really wanted to use the Top N filter). Upgrading to 2.40.4554.361 promptly brings the issue back.

This issue was previously reported, but apparently marked as "closed" with no further discovery, as seen on this URL:
https://ideas.powerbi.com/forums/360879-issues/suggestions/15693186-unable-to-open-document-we-weren-t-able-to-restore#comments

From messing arround with the files I would speculate that the error is related to a corruption of the model metadata; I managed to provoke various errors where the application seemed to think that the model could not be saved because existing entities with the same names already existed. I have sent "frowns" with those errors, with the trace files attached.

I am happy to provide the actual report files for further diagnosis if required, as the data is not very sensitive. Just please don't dismiss this issue without looking into it.

Thanks