Or maybe, it's the double-whammy? They second-systemed you and ghosted you and clammed up all at the same time?
I have experienced sitting in an international research workshop hearing my work played back to be by a PhD student. They're going to be first-to-file because they got peer review and in a commercial research domain, I didn't bother validating my idea properly in the peer-set. It was a lesson in dotting the I and crossing the T if you want recognition for prior work.