Forerunner 945LTE Will not connect to LTE

My Forerunner 945LTE connected to the LTE network and would successfully complete LTE syncs and Live Track initiation before 17.28 op system was installed. Since then, my watch will not connect to LTE and will randomly restart during runs if LTE is on. The watch works fine with LTE selected as off - but obviously it will not connect to LTE with these settings.