Hello all. This is an old thread, but I found it because I was having the same problem. That is, I uploaded a file to Files, but this did not automatically make Files visible to students. Through some trial and error, I discovered that there must be some minimum file size in order to trigger this function and make Files visible to students. So if anyone else is having this problem, just keep adding more files. Once you reach the minimum, Files will automatically become green, not greyed out, and will be visible to students.