Hey there @Clemichoux! This issue is a rare one that I can’t replicate, but I’ve seen been fixed a number of different ways.
Usually the quickest to test is right clicking on that blueprints folder and selecting “fix all redirectors” this often cleans up any redirector metadata left around and in some cases fixes file registry issues.
The next one to try is one I’m not sure on why it worked for this user, but I don’t argue with results. Backup your project first, then move these files out and allow them to regenerate in the project when you launch it. This shouldn’t work, but worth a try. If it fails you can just revert to your backup or replace the files.
Lastly, move the offending BP out of the project, save and close it. Then relaunch and replace the BP.