I think I am using the same script, but instead of using the collection "title" use the collection ID (SMS0001 etc) seems to work.! but I do not try to run updates immediately, I have a Update group targeted at the unknowns, but if you have specifics... I basically assign to a maintenance window and wait to the cycle to pick up anything missing. We update the deployments quarterly, so there are generally only a few missing. I would enable incremental updates on the collections that you are hitting, so they see things "quickly"