so you go to settings -> wireless & networks -> mobile networks -> access point names -> press MENU -> add New -> enter all the info -> press MENU -> SAVE ?

I was fighting with the same problem on my girlfriend's mini pro (it was an anniversary gift, so I was in a deep s..t) and I did not want to believe what I found as solution. Th APN list was empty using her card, but filled with the correct entries when used other SIMs in the same phone (mine e.g.).First we thought that it should be the extremely old SIM (10+ years) so we acquired a brand new from the provider but it did not help. Then I started to try to find any difference between her SIM and others we tried and worked without the problem, and the only difference I was able to find was THE PIN CODE REQUEST. The only SIM what was set up to request pin code on start was her SIM.

Then I switched PIN request off and rebooted the phone and volia: the APNs are there, can be modified, saved, deleted.

hey there, i have the exact same problem on my xperia arc since i updated to the most recent version and i don't have (or never had) PIN security. But i'll try a new simcard to see if it works

Hi i am having the same problem with the expria arc, put the setting in and they are not saving