Fixing: No package with the UUID

When running the Project Library Updater I get the following:

When I look through the directory tree, I find this file:

Containing this line:
(librepcb_package 3d0b3d88-4195-4333-92a4-6a5515fe35dd

So a package of the correct name does exist. What’s going on? How do I fix it?
I’m perfectly willing to try fixes out of the app. I have already tried a lot in the interface without changing this at all.