I get this message when launching any ROM (tested on Genesis and CPS-2 cores). I’m not sure why as I have configured the input per all the guides/videos I could find on the subject. Here is a screenshot:
Strangely, in the genesis games I tested, the buttons work but not the analog stick. In the CPS-2 games I tested, nothing works.
Here is a picture of the arcade stick, for reference:
https://www.mksecrets.net/images/newsarchive/2011/february/image30.jpg