I am Indian, I recently moved to poland and phone was working fine with both sim (local poland) and Indian airtel sim. I received an software update recently after that my Indian sim is not been detected by phone.
Scenario 1: If both sim are inserted then network is not detected
Scenario 2: If only one sim is inserted (local poland) then works fine with network and data
Scenario 3: If only one sim is inserted (Indian) then Sim is not detected and no network