Apologies for double posting. I should have read the freak’n manual.
Hairpin NAT gave me the background I was looking for. Very insightful. Then I followed the advice from Hairpin NAT - The Easy Way for my config. Hopefully this helps someone else in the future.
Can anyone explain why it worked without the hairpin rule when I had 2 bridges? Maybe it had nothing to do with the bridges at all and more to do with being on a different subnet?