After loading ArcGIS 10.8.1.14362 last week, I was in it trying to modify the symbol set of a polyline and saw that there is no longer the ability to automatically mask out a "halo" on a selection of polyline under edit linestyle.
Is this one of those items that someone just forgot to keep in or has ESRI deliberately removed this from the selection of parameters when we are modifying the polylines?
What exactly do you mean by mask out a halo?
Are you looking for something like this?