Hi @Andro,
thanks for the data.
Dould it be that you reload Dorico frequently and that you are doing this too quickly? Because the audio engine always lingers on a few seconds longer than Dorico. If you then restart Dorico too quickly, it will try to connect to the audio engine in shutdown, and that of course will fail then.
I know, this is a long existing flaw in our software, but we will address it soon.
Curiously, this has only ever happened to me with the new 5.1.70 update, so it caught my attention. Since this is a known issue, and the workaround is simple (don’t do what I am going!) we can mark this as solved without further ado.