WORKAROUND #1:
Upgrade to SQL Optimizer for DB2 z/OS 5.5, which can be downloaded
here.
WORKAROUND #2:
Have the Toad for DB2 z/OS base license key with Adavanced Tuning add on changed to a Toad for DB2 z/OS Xpert license key. This would need to be done through our licensing department, which you can contact
here.