You mention seeing this on the latest 21.0 version of FireControl. Can you send us a video of it happening? We have not been able to reproduce this in 21.0 with no keys pressed.
If you toggle quickly between jog keys and hold one down it is possible for the machine to continue moving in the original direction but this should stop if you let your finger off the key.
If it happens again, I will try and video it.
I had this issue on the Second start up of a new machine .
I was thinking of making a big red button E-Stop button as controller power kill .
If you havent crashed a CNC you havent ran a CNC.
I am not sureif it matters but now I power on the Firecontrol and then plug in the Laptop.
I also leave the head Mid table prior to shutting it down so I have some reaction time if something unexpected was to occur.
I had this same issue yesterday. This happened when I ran my fingers across the track pad. Not even jogging or anything else.
Mine does it once and awhile, but I think it’s a laptop setting issue. If I double tap an arrow to quickly it locks the motion of the key to that direction. A tap of the other direction will stop it.