While we recently have just gained access to a wonderful load remover to make runs less hardware dependant and more competititve, patches to Total War: Warhammer 3 can very well disable the functionality of the load remover and there is never a guarantee on when a fix will be made, only that it will be up to the developer's discretion and availability, and cannot be rushed.
If the load remover isn't working for you, I highly recommended first checking our guide on using it, and if it still isn't working, join our Discord server to see if it's working for everyone or you've missed a step in using it.
As you probably already know, Immortal Empires is coming on August 23rd. I plan to have the board ready by then, though we (as the moderation team) cannot say, if speedruns will be accepted immediately after release, not knowing the technical state of the campaign (also, the amount of game breaking