Struggling with the Query Tables Tool: Need Support and Solutions

Does anybody know the dark magic of returning an accurate result from the query tables tool? I've been battling this whenever I have time for the past 3 weeks and support hasn't been able to help me. I'm convinced at this point the problem is squarely the query tables tool. Today I tried using GPT-5 to get a very basic result and even it was puzzled when the tool returned nonsensical rows. The query specifies that one column can't be null - but there are null results. It specifies the correct column to return, but a different one is returned instead. Table queries are useless in this state. I used the API to get and verify all the table data and it is as expected (but certainly not being returned as such by the query tables tool). Pls send help.