Several projects switch to left speaker only

I have projects that seemingly switch to the left speaker only. I think it has to do with when I switch audio output device (built in to bluetooth). Attached is an example.

Once it switches to only the left speaker, it stays that way no matter what.

New instruments, removing or adding VST patches don’t change anything.

I originally used Native Instruments Kontakt 5, but I tested it on the Halion, and it only plays out the left.

Changing output to built-in still plays out the left speaker only.

Quitting and restarting still plays out the left speaker only.

Not every project does this. If I create a new project and copy and paste (which is my workaround solution for the time being), it works normally (works with bluetooth, built-in, Kontakt, Halion).

I haven’t changed any setting that I know of.

I tried the solutions in this post but they didn’t work for me:

Anyway, thanks for any ideas.
Piano Test (387 KB)

The project data is consistent with your experience, i.e. the port mapping data of the audio engine exactly tells that, send audio only to the left channel.
Now, the most interesting part is, how could it get into this state in first place?
To be honest, I have no idea right at the moment, but it starts worrying me, because more of such reports come in.
Therefore there must be somewhere a hidden issue that we need to fix.
Yet, we have no reliable way of reproducing it.
You say you have several projects that behave that way.
Is there anything particular that you did to those projects?
Are they D2 projects that you just loaded into D3?
Or does it only happen with newly created projects.

When it happens you could try to repair the project data yourself.
Take the project file and simply unzip it; despite the ending .dorico it is just a zip file.
You then see 2 folders and 2 files, go into the folder supplementary_data and delete the folder vstaudioengine.
Then go back and zip up the 2 folder and 2 files and change the ending back to .dorico.
Load that project in Dorico and reapply the default Playback Template, and sound should come out of both speakers.

Just FYI, This happened to me after working on a D3 project on my laptop that had originated on my Mac Mini. I used a BlueTooth speaker for playback on the laptop. When I later reopened the file on the mini, I was getting audio only out of the left channel.

Ulf’s “unzip–delete vstaudioengine folder–rezip” fix worked for me.