i have a master lock setup, 3 alike, weather covers on them. About 5 years old now. had one freeze up 2 weeks ago -but then the coupler setup froze too and I had to unpin the receiver and pull away leaving the hitch ball with the trailer. Ice is ice.
I had one a few years ago get 'sticky' and some WD40 seems to have fixed it. Keep them lubed and they're ok.
On my sheds I use ONLY master combination locks. Never ever had one fail, freeze or act up and they're out in the weather all the time for decades. One lock I used in the 70s on my school locker - still working 40 years later, been outside for 30+ of those years.