Hi,
Don't get me wrong, but your current description sounds like "I have a problem, but I wouldn't say any details about that". Please provide at least mobile application logs, and also try to figure out some things yourself:
1) What is difference between both SIM cards you use? 2) Does mobile with "non-working" SIM perform successful LU? 3) Does mobile with "non-working" SIM receive any Paging Request? 4) Does one answer to Paging Request by sending Paging Response? 5) Then, does the L1 switch to a dedicated channel? 6) What is happening on a dedicated channel? 7) ... ?
OsmocomBB is not for end users, so you should do / learn a lot of things yourself. After all, the source code is always available.
With best regards, Vadim Yanitskiy.