Can't move items to Trash – resistant to usual fixes
Filesystem errors that bedevil daily use... grrr... I had something similar to that and nothing I did: repairing the disk, using DiskWarrior and some of the tricks you tried, did a thing.

Finally I got fed up and backed up the drive, deleted the partition and recreated it and reformatted it. Problem went away. If you asked me what caused it I couldn't tell you, but backing up a drive that was basically an internal backup drive so I could re-partiton was almost as annoying as living with the problem.