Cannot delete albums, groups, etc - why?

For some reason Capture One will only let me delete one empty album or group. After that my "delete" menu item is greyed out. It is greyed out both in the menu bar and when I right click on the album. If I want to delete two empty albums I must quit C1 after deleting the first one, reload C1, and then delete the second.

Any ideas how to fix this?

Thanks!