Submit for Approval button got disabled.

Submit for Approval button got disabled for an Worksheet Manager(Supervisor) in WFC plan eventhough supervisor has not submitted the worksheet. In addition the access level gets updated as no updates allowed. For most of the supervisor's reportees the submit for Approval button is disabled. But the Supervisor+1 has provided awards instead of Worksheet Manager,which is not an issue. We tried checking whether any transactions done by the superviosr or supervisor +1 but no such transactions found in backend.