Hm… I guess the cue counts as “content” in the trumpet part, so Dorico paints it there.
Just out of curiosity: If you remove the cue, will the label stay there or will it be printed right at the “real” first notes, where you actually want it?
@Dorico team: Could Dorico ignore cues when determining where to paint instrument change labels? I can imagine parts with multiple cues without real content around.