Fixed on develop (goes live at the next publish). Root cause: the party-EXP receiver compared account ids with a raw ===, but wallet accounts arrive lowercased on the relay while they're stored checksummed, so every real-player party failed the match and the share was dropped. Now uses the same case-insensitive account compare the party system uses elsewhere (MVP bonus too). Please re-test shared EXP in a party after the next publish.

Live in the latest publish — marking this Fixed. Thanks for the report!