Yes, it's definitely related to SQL, and specifically related to the issue of determining "what record was just added". However this was (I think) working in most cases (specifically auto-numbered cases) in NT5. (In NT6 thre's a complication here, that I'm aware of, but that shouldn't be affecting you yet.)
So I think the first step is if you can make an example for me, with MsSql, duplicating the effect. Specifically make sure you get all the auto-numbering settings the same, and also the "advanced tab" settings the same.
I'll run that example through NT5 to see if I can spot the root of the issue, and then also in NT6 to see the effect there.
cheers
Bruce