Yes I think I probably had similar symptom/issue prior, to a more specifically fixed HDMI setup; via use of getedid command.
My thoughts would be to give getedid command a try (only when sure both HDMI connections from rpi4 are working as you expect) to store the known status/profile of each working HDMI connection.
It cannot hurt to use "getedid create" to store HDMI profiles such that your rpi4 "always" uses same known working HDMI 0 & 1 profiles between boot-ups, rather than occasionally switching to something that cause Video HDMI 0 or Audio HDMI 1 to suddenly not work as expected.
Note: You can always revert back to vanilla HDMI setup/installation (default installation is restored) with "getedid delete" command if it doesnt help.
I extracted following info from the log you posted in other thread, to highlight what I believe you wish HDMI 0 and HDMI 1 to be permenently assigned to and never get confused between them.