Hi.  I have an imach III P1A-S tied to Windows 10/64 running Mach 3.  For the most part it runs ok.
However, sometimes when I switch to the single step mode, it all locks up and no setting of the knobs can get control back.  What *does* work is toggling the EMO button in then back out (usually), moving to velocity control mode (V) and jiggling a stage around.  I do not have this mapped out precisely because too many combinations.  It might just be a timeout is necessary.

It also has the alarming tendency for the stage suddenly going into constant speed mode while jogging in single-step mode, which is a leap for the EMO button event!

I've also sent this to the VistaCNC support email.

thanks
Matt