The unhighlighted Scab shooters are probably Scab Stalkers (sleeveless uniform, helmet with no goggles or mask, bandoliers) and it was a design decision (Fatshark says) to have them not highlight as they are “different”. Counterfire’s description should be updated, Scab Stalkers should be more visually different, or they reverse their decision to have them being excluded from being highlighted.
Bio-Optic targeting only displays specials and elites for non-Veteran teammates and shows highlighted enemies for other veterans based on the level 30 feat they have, eg. Veterans with Counterfire will see shooters. Again, this is allegedly by design. I personally would like them to show the sharer’s targets.