@keneda Thanks for the reply. Yes, what I've done so far is remove both SIMs and the SDCard. Then reboot. Then insert one at a time in to slot 1. Then slot 2. Then swap them over. Then put everything back. Nothing heard from the Mobile ever again.

Also OpenStreetMap was showing my location..... can't find me anymore. It's been a couple of hours now. The location pin is showing on the status bar at the top however.

EDIT:
I have now done a full re-install using 0.8.9-beta and selecting the full wipe option. My network Mobile icon is now back. Both SIMS appear, and I suspect the GPS will work again (not yet tested).

I guess this means some configuration data was wiped (or now lives in a new place) during the OTA.

This was not a big deal for me as I only got UT install a couple of days ago.

Today I did the UBPorts OTA update and rebooted. Now there are no SIMs/Phone networks.
Settings no longer display the Mobile icon at all. Completely gone.
Any help most welcome.

@phone-adventures replying to my own reply (newbie thing to do I know) anyway SUCCESS!

Thanks in large part to the folks on XDA. I ended up downloading 0.8.8-beta (but maybe a later version would also have worked). It displayed the exact same issue. Searching revealed a post on the LineageOS site (I think it was) with people that had an identical issue.

The advice which was followed related to data in the user partition which causes this. So the advice was to wipe all user data (i.e. check that box). I followed that advice and BINGO everything just worked as documented.

I hope this helps someone with a Xiaomi Poco M3. I've added some stuff to the web page, but more needs to be done on that.

I'll now try to figure out how to close this issue off on this forum.

Hi. I've successfully oem unlocked this Xiaomi Poco M3 (created a web page on how I did that: https://www.electricbrain.com.au/pages/phone-adventures.php )
Recovery works wonderfully. However the install fails after download 14/14.
Over on XDA there is a thread with my issue:
https://forum.xda-developers.com/t/rom-guide-citrus-port-ubuntu-touch-ubports.4345617/
Essentially eveything stops with:
error: adb: preparesytemimage: error: {"error":{"code":1,"cmd":"C:\Users\tman1\AppData\Local1\Temp\1z2CZhpznORyjIPpqvVgfFBXFGZ\resources\app.asar.unpacked\node_modules\android-tools-bin\dist\win32\x86\adb.exe -p 5037 shell mkdir -p /cache/recovery"},"stderr":mkdir: '/cache/recovery": required key not available"}

From my (very limited) understanding I suspect AVB may have a hand in this?

When booted to UPPorts Recovery I am able to use adb to execute a shell. Everything seems to work. I can use top and see the "disk". All looks good.

Any help most welcome (I loved the FAQ btw about the "don't panic" thing).
Cheers
P