Lightroom Classic: Import from another catalog fails since last updates

For years my workflow with LR classic is as follows: With my macbook I work in the field. I do a "export as catalog" and import these catalogs on my iMac into the raid system. Most often I will work then on the macbook on certain images and when finished I make a new "export as catalog" to update the main catalog on the iMac raid. I do the catalog either only with develop & metadata values or sometimes even incl. the raw files. I then updated the catalog on my iMac raid with just the developing and/or metadata values.

Now (since one of last updates, I can't quote exactly) it doesn't work. Trying to import same catalog as update to raid fails. The new import does not see the existing images as before. When importing then with "copy new files" the import copies the exact same files to the same directory but all with ending "....-2.nef or "...-2.arw". When trying to rename the orginal folder name with these images and importing the images again to prevent double files with ...-2 at the end then LR gets an error msg that import fails!!

When I then select all images in that folder to delete them intertirely from disk it erases also the double ones that are not seen by file count. I did screendumps of everything to document it.

I have to admit that I'm more than angry because I just returned from 2,5 week trip as tour photographer and I'm now not able to deliver in time as I can't update my work with the saved developing values!!!!! I mean I have 9000 images to select and edit from. and just now LR sucks again (sorry to be rude, but I'm really pis....)