This fix may work but when you use Wifi-calling you NEED automatic mode as the "provider" switches from the main network to a "<operator name> Wi-fi". I live in a low signal area (which seems like a commonality for this issue) and my phone goes to Wifi calling in parts of the house. THIS is the trigger for it never getting back onto the main network (without reboot) when you leave Wifi. It is a bad bug as you have no idea your phone has no service, dangerous in some situations. Hope it is addressed very soon.