activation required iPhone 5s EE UK

I have iPhone 5s locked on ee uk with ios 8.4.1. I’ve been using it with x-sim evo 3.1 for over two months without a problem (calls and texts sometimes 3g). Today it asked me for activation like 15 times constantly. Can anyone help me fix this problem? Thank you.

Should I select lock carri?
and can i use the xsim on another for after lock carri is selected?