I had it before the upgrade. Also, I have been meaning to check the toolpath display. Sometimes I forget and load the Gcode before I zero the axis so the tool path may be off of the display area. I have not tried to see if there was any correlation.
If I run the machine into the limit / home switch a couple of times I can usually get it to replicate the problem; however, occasionally it does it when running a file. It may get half way through and just stop at a toolchange. I can usually get the line number, disable M4, enable M4 press the Goto zero button, and restart M4 (sometimes have to use the task manager to kill M4 after I exit the program). I can then restart M4, reload the Gcode, amd start it at the line where it stopped.
The code does not really lock up. If I disable M4 and reenable it the Gcode will often progress to the next tool change and then stop.
I will play with the machine and see if the toolpaths are showing when the problem occurs.