I went for NordVPN a while back, for geoblocking purposes. Like to leave it on all the time (sorta for extra security),
I leave my NordVPN on continuously and have found a couple of sites that don't like it. GloBird energy was a challenge until I turned it off.
FlyerTalk doesn't like some of the servers. I simply disconnect and try again. Never had AFF reject a server, yet.
My biggest problem with NordVPN is the requirement to reenter the password whenever there is an upgrade or some other matter I've not been able to determine. With a password of 20+ varied characters it's a pain to have to carry it, even in a disguised format.