Same problem here, Lumia 1520 RM-937, my phone updated to WP 8.1 Update 2 and everything was OK, then WP 10 OS ver. 10.0.12534.56 and it started to have the same SIM PIN issue, whenever I try to enter the PIN code the phone freezes, I managed to start another update so I am waiting...
Saw it too late but I tried it before and when I entered the PIN in order to disable it, the phone froze again...
Anyway , same issue after second update but a hard reset (vol+,vol-,power,vol-) did the trick...
through settings you can change smthng so that it doesnt need to apply a pin for the sim that way after applying the pin to unlock that it will work fine