Xiaomi Mi A2 + Lineage OS 11 = no mobile network internet

I have an Xiaomi Mi A2 with Lineage OS 11 installed. Calls, texts and wifi work fine but switching off wifi or moving out of range of router results in loss of internet, i.e. my mobile network does not kick in. I have tried reinserting sim and toggling aeroplane mode with no results. Putting the sim back in my old phone and the internet works fine, Any ideas? Thanks ***update*** I am been revisited the instructions on https://lineageosroms.com/jasmine_sprout/#installation and tried the below builds: - lineage-17.1-20210327-nightly-jasmine_sprout-signed.zip - lineage-17.1-20210320-nightly-jasmine_sprout-signed.zip - lineage-18.1-20210626-nightly-jasmine_sprout-signed.zip Still no mobile internet.