Let the fun begin !!! ???

[JAZZCNC]

Ok it occured to me last night in my sleep that noise on the 10v signal still wouldn't make the spindle Spin if the relay was working correctly.
So I still think you have some issue with the relay not being set correctly. The 0-10v signal just defines the speed reference it's the Run signal and relays that controls whether the spindle turns or not.
I think relay is not being controlled correctly and the run circuit is still closed. Mach stops sending a speed reference when M5 or spindle button is toggled off but the noise on the 0-10v line is causing the spindle to still spin because the relay circuit is still closed.

So only thing I can suggest now (other than you've not wired it correctly which I'm sure you have.!) is that the BOB is some how taking over controlling the relay duty's and because in Spindle setup you have the Relays enabled your getting conflicts.
I suggest to test this theory you put the VFD back into using the on board speed control PD002 = 0 and leave the Start/stop to set to external control. (make sure the vfd speed reference is set above zero for this test) I think you will find the spindle starts again and won't stop and you can't control it using F5 which if was correct it would.

If I'm correct then try disableing the relays in spindle setup and see what happens.?