Hi,
I have also been having issues with the new cellular setup using a Huawei E3131h-2 and E3533s-2 on Balena 2.47.0+rev1.
I ended up reverting the E3533s-2 to cdc_ether.
It is important to note that I have never had the E3131h-2 as a cdc_ether device.
What I noticed was that when running with just the dongle, ModemManager would quite often not see any devices (within a reasonable timeframe); when running with ethernet connected, it would much more often/faster detect the device.
What I have done now as a workaround for this issue, is to periodically (every 30 seconds) query ModemManager through dbus to check if it has any devices; if it doesn’t, I restart ModemManager (dbus query to systemd).
For now this seems to work for me, YMMV.