I have discovered that all PDFs in one Group have a Tag that I did not assign to them. This is a Tag that I have been using for other PDFs in other Groups in the Database, but not for these. I do not know how this Tag became associated with these PDFs.
The problem is that I cannot remove this rogue Tag from the PDFs in this Group. I have no problem removing the same Tag from PDFs in other Groups in the Database. When I try to remove the Tag from any PDF in this Group, it seems to be removed at first, but when I move to another PDF and then back, the Tag is still there.
I am using DEVONthink Pro Office 2.11.2 with macOS 10.13.6 High Sierra.
Could this be a corrupted Database? Please help.