Norway & Mauritius HDR HLG 4K UHD 10bit demo (YouTube App on the Cube)Yeah I see that mate, at least we know the BBC are not blocking anything (because the uhd trial shows) personally I would try a HLG file outside of iplayer, if HLG still doesn’t engage then it’s likely to be a cube issue. You can get one from here:-
Demo in Ultra-HD HDR - HLG (Hybrid Log-Gamma) 4K , captured from Travelxp HD, an Indian high definition travel channel.4kmedia.org
For further confirmation you could probably try it direct on the a90j
If it is working then the problem is the app, has anyone confirmed it working previously? If so then perhaps try to source that apk and sideload?
In the words of Ann Robinson... iPlayer - You are the Weakest Link!!