Wow. There looked to be about twenty different sites pushing #JavaScript on that job application site. Even after I allowed all (except CloudFlare Insights and Google Analytics), the submit button wouldn't work. There was a defective Date object somewhere that threw the 'then' clause of an if statement into a tizzy.

Switched browsers and it went right through. Same set of extensions, I think.

Both browsers have built in ad-blocking, so I'm going to guess that some difference in their ad filters caused the different behavior.