Trees block LoS, since a monster using soar is adjacent to no other figures and cannot be affected by terrain unless it lands, does LoS count in this, are creatures "soaring" visible above the trees or do trees still block LoS on soaring creatures?

FAQ:

Q: Do Soaring creatures benefit from terrain?
A: While a creature is Soaring, it ignores the terrain in its
current space.

Only the Soarer ignores terrain, and only in its current space. So, no, there is still no LoS to a Soarer behind a tree.

Whether there is LoS to a Soarer (or any other figure) on a tree space (with no other LoS obstructions), is currently under discussion and will hopefully be clarified in the next FAQ. The answer is almost certainly yes in this case.

hmm... so I guess it's game agreement on "while above a tree" till the next FaQ comes out, though I suspect I already know what the FaQ answer will likely be. Thanx