Printer suddenly wont print. Manual still works.

Heya all, searching for this has been difficult. Here's what happened.

I've been printing from SD card for while but decided to try Rep Host today. My first print went just fine. Afterward I saved Gcode to my SD and tried an SD print.
The printer opens the file and then immediatly goes from 1-100% as if it's printing. It never heats up.

Any idea what could cause this?
Manual control still works, manual heating and auto home still work.

Thank you,

Sometimes if you try to slice/print an object, that say the walls are too thin for your nozzle, it will do that.

I use Cura, and if I load a thin wall box, and the wall is too thin for the nozzle, it will do that. Use the preview, layer by layer if you have it, you should see there that nothing is going to print. Then you can adjust your model and reslice or find something else to print.

have a look at the file size that was saved and compare it to what you get when saving on your PC. I suspect you have just saved/copied the start and end codes.
I find the copy to SD a bit troublesome in RH but assumed it was due to my laptop as I have issues with other programs.
A thing to try:- Make sure you save the Gcode to your PC/Laptop first. Then load it to RH and then do a copy to SD.
Incidentally its usually faster to transfer onto an SD directly and not via the printer.