Hey MrMightyErik,
Our clients were using non-seamless travel when joining the server, but your comment got me thinking.
I realised that our main menu game mode had seamless travel, so host was performing seamless travel to their own server.
Obviously that must have been the difference - once you performed the console command, the host uses absolute/non-seamless travel to rehost the match.
I could have sworn that our game used to use non-seamless travel and had this problem, but there must have been something else in the past causing other problems. Thanks for your reply, even though it seemed like something too obvious, and it wasn’t directly what the problem was, it ended up leading to a solution.
Cheers!