Okay, so after of hours of testing (and great discussion from @Dave and @danronmoon, I’ve finally figured out what’s going on.
The CORS (Cross-Domain Resource Sharing) calls I was making were set to ‘async: false’ — (which I realize I did not include in my original post, as I thought it was inconsequential) this, seems to operate fine in all browsers except Firefox, where jQuery will bark at you and your ajax call will fail.
Thank you all for your help and I hope this helps someone else!