[PhOeN!X]

Please read the 1-st post regarding the change in database format. As for migrating to a new build, export/import to/from one file (one folder actually) does not work - pictures are not imported back. This seems to be a bug in the base Frodo+ code. I think I need to post a bug report about that.
You can try separate export/import, but that will create a lot of extra files (NFOs, pictures) in your media folders. Personally, I don't like that, so I've just re-scanned my videos from scratch (I've also deployed a central MySQL video library, but that's another story).

I tried building a new library, without importing the library backup, but a lot of the thumbnails are not generated here as well. I guess the only option right now for me would be to do a clean install and setup of 12.1, or revert to the RC3. I am too lazy for the setup now, so RC3 it is

Will post back if i do muster up some strength and do a re-setup. Thanks for the quick reply btw.