Can I please get your full model number, baseband version, service provider, Bluetooth or LTE, the device your watch is paired with as well as the Android version on the device?
Thank you for that information. So just to clarify, you are unable to receive calls while your device is on LTE is that correct?
Give this link a try: https://www.samsung.com/us/support/answer/ANS00061431/
Is your watch paired to your phone by using NumberSync when using the device on LTE?
It's a program offered by your carrier that allows your watch to have the same phone number as your watch.