Can someone explain the FMaskFilter Ignore Mask to me (in line traces)?

 /** Extra filtering done during object query. See declaration for filtering logic */
 FMaskFilter IgnoreMask;
 /** This filter allows us to refine queries (channel, object) with an additional level of ignore by tagging entire classes of objects (e.g. "Red team", "Blue team")
     If(QueryIgnoreMask & ShapeFilter != 0) filter out */
 typedef uint8 FMaskFilter;

What I need is to ignore a set of actors when doing a line trace by object type (all inheriting from the same class, all share the same tag), but I cant seem to figure the filter mask out from this comment.

I would also like to know how this works, as I can’t seem to find any documentation or examples of how to use it.

I’m using the replay system for instant replays so I show the duplicated levels and hide the source levels when a replay is playing, however i’m still getting collisions between actors from different levels.

I tried setting the actor components of the source levels using SetMaskFilterOnBodyInstance(1) and SetMoveIgnoreMask(2)
for the duplicated levels i’m using SetMaskFilterOnBodyInstance(2) and SetMoveIgnoreMask(1)

however this doesn’t work so wondering if there’s anything else that needs setting?