Interesting, I started playing with code with regards to the Handshake (OnStep uses lx200 standard) and found some interesting behaviour at least on OnStep V4 & V3. I'm not sure if since I never touched the handshake that's always been there, or if it's a new thing.
When I first plug it in, it fails for a while, but if closed (Stopping indi and restarting) and reopened it works fine. This also works with the lx200_teamastro driver. This is USB based. I'll look at it more.
If you can, tell me if you have the same behaviour?