Similar thing happens from time to time (more often than before) after update to 4.5 of Xperia XA2. Sms fails to be sent in 4G. Sms sending is repaired neither after restarting the connection services via tools nor after restarting the phone. It starts to work only if I restart the phone in 2G mode, and then it also works after switching to 4G. It is strange as XA2 has not got VOLTE.