"0xA000821 - Library Error - incompatible storage media detected in robotic library

We are experiencing the above error when trying to Inventory HP C7972AN LTO Ultrium 2 tapes written to in 2007.

Having read Article:000042258 none of the solutions apply to us ie We don't use Bar Code Rules and All Media types are checked for the drive.

Can anyone suggest any other possible solutions or logs to investigate further or pass onto Symantec for deeper analysis?

Thanks