I have a few gen 5 Glock 19's. I have a variety of OEM magazines ranging from LE/Mil restricted marked gen3 mags to gen5 mags. All of my gen 5 19's will drop them free, no matter the generation of the magazine, so long as it's a gen3 metal lined magazine or newer. I own one Glock model 45 and it could care less between the gen 4 and 5 magazines as well.
I would take the one magazine you have that doesn't drop free and either pitch it or mark with a paint marker, for range use only. Right now OEM Glock magazines are cheap. I'd buy a new magazine (or 10) and drive on.