TTIG is not yet supported in V3. Did you attempt a forum search? This has been well covered in recent days/weeks. Leave on V2 for now and when the V3 TTN CUPS instance is ready (a few weeks/months?) migration will be possible. Leave it registered in V3 & V2 - DO NOT delete any registration information yoou have loaded in either system as re-instating may be problematic/not possible.
@Jeff-UK…sorry…I checked around but I didn’t find anything…to be honest I didn’t check fro the TTIG. I have already delete and add it again many times…I will leave the last one…thanks