I believe I have got to the bottom of the issue with the campaign not progressing; the edits I had made to allow for Reggie's kill on the mission of the 16/11/44 seem to be the issue, as removing all of those references allowed me to roll the mission forward to the 18th on my private test server.
This means that - in PWCG at least - that this kill is unrecorded. However I will be leaving it in the 485th scoreboard for obvious reasons.
To avoid any further issues, could we please avoid jumping in as spectators to gunner positions - it was raised as a potential cause and I have not yet had the opportunity to eliminate it as a second reason for the lack of AAR acceptance, so busy was I trying to establish the primary cause for the failure. I'm sure you are starting to get somewhat incredulous at repeatedly having to fly the 17th November, so until I can run some further tests and definitively announce that it's okay to, please DO NOT OCCUPY GUNNER POSITIONS ON OTHER PLAYERS AIRCRAFT for now.
Tuesday the 5th of January 2021 is currently a go for P-38 campaign.