The Grobda arcade core isn't working properly - primary button is "shoot" and works, but there is supposed to be a secondary "shield" button which does not activate. The core allows you to map a shield button on control remapping, but it just doesn't respond in-game. It's not a dip switch setting, and the shield appears in the game's attract mode fine, so it's not a strange "shield-less" rom.
Verified not working on multiple MiSTers.
The Grobda rom uses the "The Tower of Druaga Inc" core - (Which includes Dig Dug II, Mappy, Motos, Super Pacman, Pac & Pal, Pac-Man & Chomp Chomp and Grobda)
Can anyone else verify this?