In E11 now, when I try to create a quote from Case Entry, getting error - This is a duplicate entry of an existing record

Our Pilot, Education, and Third databases were updated to E11 and while testing in Third I’ve run into an issue. When I create a quote from Case Entry and the quote opens, as soon as I attempt to update the Territory and Salesperson, I get an error saying, “This is a duplicate entry of an existing record.” This error prevents me from saving or creating the quote. This is not an issue in Live.
I’ve checked for any Data or Method Directives, but there are only change logs (which I validated). What could be causing this, and how do I fix it?

Also, what is QSalesRP listed in table?! - Ok, I ran a BAQ on that table, I’ve never seen it before, didn’t even know it existed. It’s in Live too. Good to know. Okay, so even more confusing, since this table tracks the quote and last changed time/date, etc. How could a duplicate entry exist?

Have you opened a ticket with Epicor? Can you replicate it in the Demo Db?

I have not yet opened a ticket. That is next, if I can’t find the answer here. I can’t duplicate the issue in Pilot, which is strange since both Pilot and Third were both updated to e11. When you say the “demo db” I’m not sure which one you’re referring to?