Hooray! I found the issue!
It seems there was a glitch with the last working session. After I deleted all the files in the “workspace” folder, the synthesizer started working again.
@Mitch I
workspace.zip (6.5 KB)
don’t know who the developer is, so I’m passing this valuable information to you. This was what caused the problem with the synthesizer, and I’m sure you’ll find the reason.