Sim update 6 beta, PC, Steam:
To reproduce: start a flight at or open in SDK scenery editor a scenery addon with vegetation polygons located near runway.
Trees graphics setting is set to ultra.
Actual result 
:
NO trees are drawn inside the vegetation polygons.
Looks like ‘exclude vegetation around the runway’ option is applied to a much more larger area around the runway than before and is applied always (even if is is NOT enabled in runway properties).
Expected result 
:
trees are displayed within vegetation polygons. No such problem exists in stable SU5 Steam PC version.
P.S. I’m ready to provide the scenery that was affected as well as it’s SDK source package if needed for the investigation, please contact me.