Yes, to solve the second sim signal/connection problem I turned on airplane mode, and then turned off, and second sim start working well.. (not for long )
I don't have any apps which might bê trying to automaticaly switch between 2G/3G .. This happens without data on..
This happen without any apps intalled...
I did a clean install ( wipe factory reset, cachê, and dalvik, before and after flashing)
My 2G/3G configuration is:
Sim1 - only WCDMA
Sim2 - only GSM
The solution it's turn airplane mode on, and turn it off, and Sims start working again normaly, but this Will not solve the problem for long time... I receive lots of work calls, and this only happens on second sim... I allready change Sims.. And the problem it's on the second sim slot... I test revert to official stock mk3, and this doesn't happen, only happen on cm11 ROM's...
Right now, I have no idea what's the problem. You'd have to experiment and report any other thing you find.
What if you change SIM1 to GSM and SIM2 to WCDMA? Or both to GSM? Would the problem still occur?
The best clue would be to find the exact action that you can perform to trigger the problem, but that's not easy.