Hello! The same issue can be reproduced on macOS 27.0 Beta (26A5388g). I'd like to add some additional info. It seems like sometimes FSKit picks up .xcarchive files from Xcode/Archives on my machine, instead of my app's extension in /Applications. It also looks like this affects DerivedData too, as I'm forced to delete pretty much every intermediary folder, then deregister the extension from the system settings, restart fskitd and run the correct version of the app and then register the FSKit extension. I'm not sure I understand the reason behind making the OS scan for the module extensions outside of /Applications, ~/Applications and /Library/Filesystems. I'm not sure if I should create a new bug report or simply wait for this to resolve, but it seems like a somewhat serious issue. Please let me know if you need additional info.