I had similar issue on SXT LTE and WAP LTE with R11e-LTE. There was message that there is new version of modems firmware but modem can't download it and no traffic is passed by LTE interface.
To bo honest on WAP LTE I connected it via ETH1 to my home network and made two things. Updated the router board firmware and set NTP Client. Than modem somehow download the new firmware and everything worked. With SXT LTE wasn't so easy and I currenlty don't remember what's helped.

Try with 7.15.0 I have no issues with LtAP that is very similar.

Regards.

The latest:



Regards.

With stable 7.16 release all fine?

Regards.