@Deanna88,

Do you happen to know if the device's traffic is being blocked or limited by a router setting, or is a part of the IoT network? If so, try removing these settings or placing the device on your guest network.

Normally this behavior occurs when your camera cannot connect to TP-Link Servers, which forwards the connection back to your phone. Does unplugging and replugging the camera allow you to see the live view over LTE? 

Depending on your router, you may try disabling any settings that could cause the camera to disconnect or switch nodes, I would also recommend trying to change your DNS server to a common service to ensure your traffic is reaching TP-Link servers from your home network.