On OSX there is an issue that requires you to specify the file extension. Aside from that, the only thing I can think of, is that the path specified either is located in a folder that doesn't exist, or there is an permissions issue preventing you from saving anything there. Choose another path and try again. Use a small scene with just a box or something.

Yup was match photo... I was able to delete the photo, revert to the same camera view and it worked. So weird, it was starting to frustrate me a bit.