With the new version, I get the attached popup. I have not seen the popup with previous versions.
I don't think that I have any decryption software installed, but I am not sure. MakeMKV seems to rip without problems if the warning is ignored.
Please advice me which running programs to look for.
MakeMKV throws that up when it thinks the DVD/Blu Ray has been processed by another program. It really can't tell the difference between a disc that is being processed on the fly or one that was processed years ago and that you're now re-ripping. It's also possible that it's giving out false positives. There might be something on your PC doing something MakeMKV doesn't like or there might not be. You must know what's installed...