No data roaming on custom ROMs for Z00ED

[AnnaVR]

I've had stock MM for two years, but recently it was starting to get really slow so I decided it was time to install a new OS. I've tried XenonHD, Lineage 16, AOSP and Lineage 17 but all have the same issue: I just can't get the mobile data to connect. I've tried all the common fixes for this issue suggested on the internet, like toggling airplane mode on/off etc, and I've checked that the APN settings are correct, allow data roaming is enabled and my data plan is still active.
I think it's some kind of issue with the ROMs, because someone else has mentioned that XenonHD won't connect to data while roaming. I'm currently residing in a European country that isn't my home country, and using the SIM from my home country since the provider has good value for money data plans and the EU has recently made it illegal for them to charge extra for roaming within its borders. So I think the devs need to catch up with the times and realise that data roaming is now fundamentally important for some users. Unfortunately, it looks like they have abandoned the ROMs they have put out, so I won't be getting any help from them directly. Does anyone else have any idea what I could do, apart from reinstalling stock MM? And I'd rather not buy a local SIM card right now since I'll anyway be moving to a different country in a few months.

 

[AnnaVR]

I've since also tried ViperOS and MIUI 8, but still no data. From Lineage 17 onwards, my phone was also showing the wrong time and date, so there seems to have been some additional issue with the network connection (even though I could make and receive calls). I also noticed that if I would try to manually connect to the other available network here, immediately I would get the message "Unfortunately, the process android.com.phone has stopped."
So I've gone back to stock MM for now and the data came back. I would still appreciate if someone could fix this issue with the custom ROMs though so that I could use one. I think they are faster than stock and it would be nice to explore their features. It's a shame I can't use them just because of one issue. I will probably still need the data roaming when I move to another European country in a few months time.