Exploding music to two different staves when in two voices

I noticed something curious and frustrating with Dorico 5.latest yesterday. I had recreated horn parts from an old march arrangement and transposed them from the original horn in Eb to horn in F. No problem. I had recreated them like the original so that horns 1 and 2 were on one staff and horns 3 and 4 were on a second staff. Almost all of the parts were chords entered into upstem voice 1. However a few measures contained notes which had to be added into downstem voice 2.
Once I completed the first stage of the project, getting the printed output and layout to match the original pages, I decided to create individual parts for each horn, thus added 4 extra horn in F players (and staves) to the score.
The problem came when I went to explode the two original parts onto the four new staves. I followed the instructions from the online manual, which were to highlight the music to be copied (thus the entire Horn 1 and 2 staff), press ctrl-C to copy the music, then highlight the staves to be exploded onto, select “Edit / Paste Special / Explode.” The result was that ONLY those few notes which were in separate voices exploded properly onto the Horn 1 and Horn 2 stave – the chorded notes were pasted into only the Horn 1 staff. However if I selected only a group of measures which had only Voice 1 notes and followed the same procedure, the chorded notes exploded correctly onto the two selected target staves.
My question is “Why didn’t all of the selected music explode properly when I select the entire Horn 1 and 2 original staff and copied that and tried to explode it onto two target staves?”
It was extremely frustrating for me until I finally noticed what was happening and experimented. Needless to say I did finally get the separate horn staves completed but it took much more work than i thought it should have.
What did I do wrong?

For clarity, I’ve just posted this response on the FB group:

Explode’s not very good at handling changing textures. If some of the material’s chords in one voice and some of it’s split across two voices, you’ll need to do the exploding in chunks. That’s just how it is (and I do hope it’ll be improved in future).
Meanwhile, if you could not post the same thing here and the forum without linking here to the other place, that would be much appreciated - right now you have a situation in which the same sort of feedback could be happening in two places, separately, which is irritating for those of us that keep an eye on both.


I’m sorry about the cross-posting without linking. It won’t happen again.