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.