Please if anyone can check this: go to contacts, press any contact and then press and hold call button and then this menu should pop-up which will let you choose a SIM card by which you want to make a call. Now. My both SIMs have phone numbers in them but for some reason only SIM 2 is only showing the number.
How about you?
For me, there is actually an option to set the default and I can chose 1 or 2 
