For some reason in my condensed orchestral score, Horns 1 and 2 are grouped with the woodwinds for the first two pages of my score, and then, correctly, with the brass forevermore. (There are 4 horns, and 3 and 4 are with the brass the whole time).
I know there must be a quick fix for this - but can’t seem to find it.
It sounds like you may have inadvertently created a bracketing change at the start of your layout. Make sure View > Signposts > Bracket and Barline Changes is switched on, and look for a signplst labeled accordingly above the top staff of each system. When you find one, delete it.