FWIW,
I've had the same problem on occasion.
What I found is that it isn't even necessary to bring the funky tape back
from offsite.

If the Q CONTENT shows nothing on the tape, you can update the status to
READONLY (instead of offsite), and run the AUDIT VOLUME with fix=YES without
checking the tape in.
TSM detects the "missing or incorrect information", and updates the data
base without calling for a mount.
Then you can set the status back to OFFSITE, they will be either EMPTY or
PENDING.
You can let them come back whenever you retrieve tapes from offsite.

Just saves 1 step.

Wanda Prather
"I/O, I/O, It's all about I/O"  -(me)