[Q] If sim1 is on 3g sim1 is offline topic

Hi guys, i noticed this big issue using my phone.
If i enable 3g for sim1, sim2 is completely offline (it can't recive or do calls).
If 3g is disabled, both sims work well simultaneously.
As you can undertand in daily use outdoor is a big problem.
Test done in MIUI v37, v45 and v47, Carbon rom, Mooke and CM11.
Have you the same problem? Do you know how to fix it?

Thanks