Z Value During Program

An odd one for me that I can’t seem to find the issue with this forum or Google.

I was cutting out a couple smaller pieces of acrylic with my MPCNC last night and about a minute into the program it froze. I look at my laptop and the Z value in repetier is red so I checked all of the connections and everything looks good.

I’ve ran this same small program in other spots on this acrylic sheet previously with no issues at all. The only difference this time is that I slowed down some plunge speeds and feeds. I also tried this program in a second location afterwards and it froze in the same spot.

I can get the code after work but I am a bit perplexed as to why the Z value dropped out like that. Of course i don’t have a ton of experience either.