Hi Mark, If you can do inserts but not selects, the class might have row security enabeled.
Is there a parameter  ROWLEVELSECURITY = 1, and a method %SecurityPolicy present ? In that method, you can exclude rows based on e.g. $username and $roles. Even if your user has the %All role, you could be excluded to see a row in this security.
If you see that, you can or create the correct user/role, or set the parameter to 0 (and rebuild all indexes).
Can you send the class definition of one of the tables, so I can try the class on my server ?

Or in Terminal :
Do ##class(%ResultSet).RunQuery("DocM.DocumentImage","Extent")
(This should do the default query Select ID From table)

Hi Mark,
Can you post one of the class defintitions here ?