Not sure I'm in the right place but..

Using TVHeadend on Ubuntu 20.04 as server with 2 x DVBSky S952 dual tuner cards (previously had quad LNB with same software/kit as now - no issues with using all four outputs).

Moved house and new house had twin LNB only so thought I would go unicable and up tuners in PC.. so have just had a GT-Sat GT-S1DCSS24 (1 legacy+1 unicable output) LNB installed - cannot run 4 cables down as current are in wall and dont fancy drilling through 60cm.

Cable goes via GT-Sat GT-SP41 4 Way Satellite Splitter to PC server

I can see all Montage Technology M88RS6000 tuners in TVHeadend; can configure/use Universal output ; can configure/use Unicable using I or II frequencies / userbands

Problem is that tuner 2 on one card doesn't show satellite config field - everything else is OK.
So far have:
1 swapped to a spare S952 card - no change
2 swapped cards in PC - no change
3 swapped /replaced all cables - no change
4 removed 'legacy' input to PC and swapped config to Unicable - input still works on TVH

Not sure what else to do. Is this an LNB issue? Is the splitter causing power loss so LNB not 'detected' by TVH? (although WoS page says it is for unicable) A TVH software issue?

Any suggestions please!