How to unlock a locked folder on external drive when locked checkbox greyed out

I use an external hard drive for Time Machine backups and to store some larger video files in a folder called Videos. The Videos folder on the external drive is now locked and I can't unlock it. I go to Get Info, hit the lock icon and enter my password, but the "Locked" checkbox is greyed out in the General section. In the Sharing and Permissions section, instead of displaying my name, it says "Fetching . . ." and I can't change the Privilege from "Write Only".

Anybody know what's causing this or how to fix it?

Thanks.