Cubase 11 Pro cannot find project file

This is an issue I have experinced over the last weeks.
I have been recording a few songs in several sessions, so working on these projects is a continuous process. I work with several project files, all labelled with song name and date and “-REC” or “-MIX”, so I have a project with no plugins for recording and another with everything else where I import the tracks for mixing and editing.
Now: It happend a few times that trying to open the recently used project from the hub led to an error message that the file could not be found, e.g. “XXXXX.20220213-MIX.cpr”. Said file was indeed not in the project folder anymore, instead “XXXXX.20220213-MIX-01.cpr”, which I can of course rename to use. I just hope it has the last edits in it. I did not create a new version of the project, so Cubase did the renaming by itself - apparently losing the original file on the go.
I am recording to a Dr0pbox-folder on my local HD, during recording and mixing the mirroring is paused so Dr0pbox doesn’t accidentaly lock any files.
Anyone else having this problem? Any work-around? (Cubase Pro 11.0.41 Build 448)

But it is able to delete files by itself… this is not a good idea…

Don’t use a dropbox folder for recording and editing.

Is it? Never heard of this and never experienced it with any other files or folders.
So there should be some entry in the DB file/activity history? There is not.