I have a score(see pics) with horns 1-4, i created custom condensing groups 1+3 and 2+4 but only 2+4 get condensed… why
Hard to say for sure without a project, but for starters: in Notation Options > Condensing > Pitch Crossing, how many notes are allowed to cross within a phrase? In your screenshot, there are quite a few places where horn 3 is higher than horn 1.