Well aware and this is why we are stumped by it. DBAs and everyone else, so I was hoping someone would have encountered. It blocks, for no definable reason, there are two code parts in my post, the first is the code for DEV and works in SIT, refuses to work in UAT at all. Until we remove the subquery and replace with a table variable, then all is fine. Not sure how I can explain that blocking is occurring that does not show up in the blocking list and the query which takes about 2 seconds to run normally clocks until the timeout is reached. Don't even see a deadlock victim statement. Literally no definable answer on this we can determine. Guess I might have to resort to getting MS help.