Yep, on my most recent trip LHR-ORD in F, all the priority bags came out pretty much dead last. (It was little solace that my bags were the first of the priority bags.) I was standing there with some other premium cabin pax and one of them commented that his bags often came out last on his recent international travels, adding "I'm just going to tell them not to put the priority tags on anymore". I'm not sure he was joking.

I have long known that priority tags mean nothing on domestics, but I have had pretty good success with them on international flights. I hope this is just an aberration, as being able to get the bags and get through customs quickly is a nice perk.