Quick update for y’all. I spent some time this week investigating the problem and found myself unable to reproduce it, because, as it turns out, Epic has already updated the P4 client version in the ue5-main (UE 5.5) branch: https://github.com/EpicGames/UnrealEngine/commit/70b1b9ffff1b8e3559de97ebac01610f0ea12b8f
I doubt this will be backported to UE 5.4 or earlier officially, but the change looks to be self-contained such that you could probably pull in the patch to your own copy of UE if, for some reason, you want to use the native client instead of the external executable.