So, Nix are the most specific club in the world.
They play in AFC league and are based in OFC country. They can't play in AFC competitions as they are based in OFC country, but can't play in OFC competitions as they play in AFC league.
There is a club of similar statue here in Europe, Vaduz from Liechtenstein. They play in Swiss league, but can't qualify to UEFA comps via Swiss league - they can via Liechtenstein Cup, though.
There are also cases like the Copa Libertadores that allows CONCACAF Mexican teams (By invitation) to compete in that CONMEBOL competition.
Also note EVERY NZ club that has played in an Australian league while both in OFC and being Amateur/Semi pro then Fully professional have never been accepted into any New Zealand league for OCL play off or reserves side for one reason or another.
I hope its about to change but as you can see - There is a lot of politics and haters for clubs wanting to move forward with the times.