bpmcl

Found the problem (at least in my case). I was using a VPN (specifically NordVPN), and that is somehow blocking access to the Launchbox URL, which is, I assume, making an API call to pull the list of supported MAME versions and silently failing. It worked once I realized this and paused my VPN. Hopefully this is helpful for someone.

Sorry, but having this exact same issue. The "Next" box can't be clicked, and the "Select romset version" dropdown doesn't appear. Editing the path or browsing to another directory doesn't make a difference. EDIT: Including screenshot. Also tried to add a trailing "\", but that didn't help.