Depends on exactly where you draw the line at "breakthrough", but there's been at least a few novel and interesting results coming from outside mathematicians.

Depends on exactly where you draw the line at "breakthrough", but there's been at least a few novel and interesting results coming from outside mathematicians. Recently for example there were https://old.reddit.com/r/math/comments/1uxj3cy/after_openais_cdc_proof_announcement_gpt56_used_a/ https://old.reddit.com/r/math/comments/1uxj3cy/after_openais... from Phillip Kerger at Berkeley, and https://www.erdosproblems.com/forum/thread/119/proof-claims https://www.erdosproblems.com/forum/thread/119/proof-claims from Samuel Korsky at Two Sigma (the latter of which was more of a collaboration between the human and machine, not a one-shot like several of the other results we've discussed).