As I thought, Peter, your file opens and behaves normally now, at least for me. While this is something the Dorico team should address, it might not be easy, as the problem isn’t easily reproducible.
Jesper, nice work! It’s fun, isn’t it? I question: how did you get the whole bar rests? I’d tried to do this unsuccessfully in var. 3 and Daniel said that this wasn’t yet implemented in Dorico. Those were whole-bar rests in 12/8. I noticed that your whole bar rests can’t be edited to change the vertical positioning, and that trying to select them causes the properties panel to act a bit strange.
Please forgive me but you’re missing a couple of ties (bb. 6-7 and 11-12) and the last note of the first ending (b. 33) should be C#. Speaking of endings, I can imagine that that’s one of the problems with implementation of repeat endings in Dorico: the notes preceding each ending are tied, so you need them to tie over to the first ending but you also need tie ends at the beginning of the second endings. Finale can do this but you have to enter the bar-database to get them to show.
I’d also tend to notate this consistently two voices on each staff with stems up and down for each voice. I know it’s easier to read with the notes on the staves of the hands playing them but…