I know this was covered on an earlier thread but I am now having the exact same issue since upgrading to v4.64 . I have followed the previous thread and its instructions and here is what's happened / happening.
I have downloaded v4.64 from the centroid website here: https://www.centroidcnc.com/centroid_di ... taller.zip
I have renamed my v4.50 folder then installed v4.64 MILL as a new install, I have a milling machine and a PRO licence. I have tried to restore from a restore file and got the spindle problem, I then uninstalled cnc12 and reinstalled a completely fresh install, then I manually entered in all my parameters (I have photos of all previous settings from v4.50) in case it was an error in the restore file but it is still occurring.
When I turn on the machine from a power down state and everything has booted up and loaded, I can run the spindle, as soon as I try to do a tool change either from MDI or a NC program I loose all spindle responsiveness. I am running 0-6v analogue with Outputs controlling FWD and REV. When this error happens the outputs don't function and I get no voltage change at the spindle control terminals on the acorn board. to get the spindle to function again I must power down the acorn board and restart cnc12.
I have attached my most current report.zip file.
Help me cncKeith your my only hope (that's a star wars reference

Thank you kindly in advance
Russell