Z-axis Not Moving Before Printing

[AyeNeNAy 0]

I'm taking a Research and Development class at my high school, and as a part of it, I'm printing parts for a VR Headset.  We're using an Ultimaker Plus(I think) and we have small issue.  When I load the gcode to start printing, the bed doesn't adjust and the nozzle just starts extruding leaving a squiggly mess in the outline of the part.  And this only happens with the one file! We've tested it out with other gcodes and it worked just fine.  I'm on a bit of a deadline so I would appreciate any help.

[rebekah_harper 56]

Ok I assume that the G-Code files are not newly generated ones after the problem G-Code?

I would suggest you use a different model and generate a new G-Code and see if it happens.

when you say the build plate doesn't move. I am hoping that all axis go to Home this being the build plate goes to the bottom.

if not, what height is it at when it start printing? is it the height it was priming the nozzle at?

just to confirm it's the UM2+ ?

if so sometimes I have to just turn it off and then on again and on two occasions I had to do a factory reset.

you may need to reinstall the latest firmware but that is easy enough through USB or Card