This issue just started two nights ago. Up until then, I wasn't having any problems. But now, when I save a GCode from an STL, it won't print. My printer (Monoprice Select Mini V2) will just sit there, warm up a little bit (not as much as it should), and not do anything while the progress bar fills up. After a couple of minutes, it will "complete" even though nothing actually happened. I have been using Cura 15.04.2, so I tried installing the latest version but I get the same results. I thought maybe it was a problem with my printer or SD card, but files created with Slic3r work just fine. I also have no problem printing files that were created with Cura prior to the issue. In fact, I'm printing one right now. But for some reason, if I create a new GCode, it won't work. The source of the STL doesn't matter; it happens with models I create myself as well as ones I download from Thingiverse.
Another odd thing I've noticed is that if I load one of these GCodes in Cura, it will be completely blank (or will only display the first 42 layers), but it shows up just fine at http://gcode.ws. GCodes made with Slic3r display in Cura without any issues. Based on everything I've experienced so far, the problem seems to be specifically with Cura. I haven't made any changes to my settings recently, so I don't know what's going on. Any ideas?
If it helps, I have attached an example STL (a base from Thingiverse that I have modified) along with a GCode created with Cura and one created with Slic3r.