It looks like you are using now() fairly often in that query. That would, of course, give different results in different transactions, but it could also give different results if a) the things you are comparing now() to are timestamp without time zone and b) the session time zone of the user doing the refresh is different from the session time zone of the user running the query. I'd also be suspicious about any other timestamp comparisons that aren't comparing timestamp to timestamp or timestamptz to timestamptz.
