"Robot Code" won't turn green, but no errors are displayed

[ARaine]

I had this issue as well, and like your problem, it did not appear to be a code issue. I had originally modified my code slightly (just some constants) but the code would not start and no error message displayed. The project had been working just fine up until this point.

I found a temporary fix, which was to reboot the roboRIO either by pressing the button on the box itself or to click the "reboot roboRIO" button in the Driver Station.

After the reboot, the robot code light came on normally with the new code I had deployed. I do not know why this happens but I hope a simple reboot is a much easier fix than what you had to go through.