By jiggitty, give it up to the GREP newbie. I think I figured it out:

‘\u

This came in handy: https://creativepro.com/grep-and-text-metacharacter-cheat-sheet.php

.’\u apparently searches for any punctuation followed by an apostrophe followed by a space then an uppercase letter. It is finding instances where this happens between paragraphs, but I don’t mind.