I haven't seen the LHGG LTE6 LTE configuration screen, but assuming it's like the Chateau, the 3G / LTE ticks should be above the band selection. For example, on mine I have '3g' unticked:
You can try also typing the following command in the MikroTik terminal:
/interface lte set network-mode=lte 0
The '0' is a zero.
You can try also typing the following command in the MikroTik terminal:
/interface lte set network-mode=lte 0
The '0' is a zero.