Is there a reason my CTE with a basic subquery in the second stage of the CTE is failing?
Let's pretend for a moment that CTE_RealAudit is a normal table...

You're querying it twice! Once to get the list of Minutes values, and to get all the other fields for those rows that have a Minutes value (oh, and surely it always will have, unless you have NULLs) in the list. So yes, that's going to take a lot longer than querying it once.

So that's why it's taking much longer. But I don't think you need to query it twice at all - have a good think about the logic you actually want, especially as it's not a normal table, but rather a complex subquery over a view.