My batch scripts I added to a lister menu stopped working, and instead opening Notepad++. I realized why: I changed the default action for batch files from run to open in Notepad++. I did that for a variety of reasons, including security as it prevents accidentally executing them.
It's not a bug exactly, it's probably reasonable to use the default action in 99% of cases, but it does mean you can break Opus by changing your Windows settings.