If I input dashed barlines into a section with aggregate time signatures, the measures do not get saved correctly (the reason I am trying to do this is dashed barlines from aggregate time signatures do not span multiple staves)
e.g. initial input
You’re getting this result because you’re inputting dashed barlines manually, which is an override to the time signature sequence (Dorico considers barlines to be connected to time signatures, because it’s the time signature that determines how frequently bar numbers should appear).
The automatic dashed barlines that get shown within bars for aggregate time signatures can’t appear on the lower staff, because it’s showing a full bar rest.
If you want to break up those complete bars into rests of appropriate durations around the barlines, you can input explicit rests on the Alphorn staff.
Ah, I uploaded the wrong image for “initial input”. I want the dashed barlines to span all staves
This is what I meant to upload, and which is not saved correctly after reopening
I duplicated your example using Dorico 4.3.31 and successfully saved and reopened it, but the same project did not open with the correct appearance using Dorico 5.1.81. The behavior you have experienced is a regression in Dorico 5.