Hey Splint,
I don't have a clear answer, but I have been troubleshooting a similar issue. Did you leave the PoExtension cable connecting the Pokeys57 and PoStep-XX drivers (assuming you're using PoStep drivers) after your initial configuration? This cable can be left on after initial config, but should be removed after (unless you're wanting to monitor the drivers using Mach4, then you'd still need to disconnect pin 1 from that series). My setup with the PoRelay8 started working again after I removed that flat cable. Hopefully this helps!
Cheers,
Noah