In Preference of Dorico 3.1 Pro under macOS 10.15.3, “Follow playhead during playback” is selected and it works in scores.
However, I have realised that it does not work because playhead does not appear in parts.
Is it intended behaviour?
Unfortunately I can’t see anything obviously wrong in this project, though there are quite a few warnings. Have you created new frame chains in layouts? If you have then there is a known problem where those do not currently scroll during playback.
No, a frame chain is different from a frame break. Music frames can be either master ( with a prefix M, created in the master page), or layout (with a prefix L, created independent of the master page). Music frames can flow from one to another in a chain in whatever arrangement you set. If you create a layout frame chain, it affects playback.
It’s definitely Master Frame Chain related. If you set your Default Part Master Page to use the MX Frame Chain rather than the MAC Frame Chain (I’ve never seen an MAC Frame Chain before) then the playhead will show correctly.
For Full Score Layout, I created the following Master pages:
For Part Layout, I created the following pages:
After creating them, I realised two instances of “Cover” are slightly different.
While working the project file, Dorico 3.1 was released.
I imported “Default Full Score” and “Default Part” from a new Dorico project file created using Dorico 3.1.
I overwrote these files into exiting “Default Full Score” and “Default Part”.
I then deleted “Cover” in Parts Set, and imported “Cover” from Full Score Set.
Is MX the edited and crated layout in the open project file?
Is MAC the imported layout?
Your score and part layouts (at least the few that I looked at) aren’t actually using the imported master pages; they’re using the original master pages. I don’t know how that MAC frame chain came into existence, but the fact remains that it’s not the one you should be using.
Ah, that’s why. When you create a master frame and save it to a master page, that letter placeholder is taken in Dorico’s mind, even if the master page gets deleted.
No, you can’t really “reset” without importing your flows (and master page sets) into a new project. You don’t have to eradicate the extra letters, though. As long as your frame chains are selected correctly, it doesn’t matter what letters they display. And as you can see from the frame chain dropdown, if a frame chain is no longer in existence, it can’t be selected from the list anyways.