When a tape goes to suspect, this means that the tape was locked so it prevents any other data to be written to it. Why does it do that? It happens when it finds portions of the tape that does not read properly so it's unrecoverable and it protects it from being altered any further.
From here if you do not have the data that lives on that tape on your storage, you will need to recover the data back to platform and then back that data up to a new tape. If all the data still lives on the Platform Storage, then you may write the data to a new tape. We do not suggest using this suspect tape unless it was cleared and tested for next usage.
Click here to learn about recovery.