@ulrik it can easily be recreated by adding a preset to preset browser aplay and stop button to your interface hooked up through param id and process id and a drag drop midi with a floating panel compiling it and trying to run midi through the midi player after strictly from the interface the preset browser might not even be necessary i will check that out tomorrow as its 4 am and i need sleep. It seems to be something to do with the compile button or the way the processor id was hooked to the play button it might be a bug