Too little time to enter puk code
When inserting a new sim card, the puk code must be entered, but the screen goes black after a very short time ... too short to enter the puk code and a new pin code twice, and when turning the device on again the puk code was cleared.
I did try changing the display sleep period to 15 minutes, but that didn't have any effect.
I have tested on Xperia X, Jolla C and Jolla 1, all with the latest update, and found the problem on all.
I had to rehearse entering the puk and pin code, and make a dash for it ... it took several tries any way ;)