If you have not upgraded to 7.18.2, you really should do that first. See https://help.mikrotik.com/docs/spaces/ROS/pages/328142/Upgrading+and+installation .
If you’re already running 7.18.2, make sure the LTE fireware is updated - that on the lte1 interface dialog. There also the firmware, which is in System > RouterBOARD, which may require a reboot.
If everything is already update-to-date, then can you post your configuration. You can do this via Terminal:
:export file=export.rsc
and the got to Files and download the export.rsc, and cut-and-paste the text here.