I don't get it, is this a known issue or not? I'm assuming that since your profile has the flair "Minus Backroom", that you're either a developer or at least a beta tester. If an entire section of the game doesn't work (2-player multi-man brawl, 2-player home run contest, etc), I'd assume you'd have gotten bug reports or complaints by now.
Is this seriously the 1st time anyone has reported this? Does this Brawl mod have so few active players / testers that literally no one has noticed a relatively significant portion of the game is completely broken? From your responses, it sounds like this is the case. It'd be nice if at the very least this was acknowledged on the download page, maybe a list in bold red under the download link saying "WARNING, KNOWN BUGS: 2-player multi-man brawl and 2-player home run contest causes crash, etc, etc..." so players knew what major glitches / bugs were present in 4.0b.
Considering that Project M has ceased production, this is probably the only major Brawl mod still being developed. I understand that the developers / testers are probably made up entirely of unpaid volunteers, but it would still be nice if major issues / bugs like this were clearly marked as such. Therefore, instead of people asking if such-and-such bug has been reported, they can quickly browse the list of known issues and see if theirs is addressed. If not, they can report it and add to the list, etc.
Sorry for the rant and no offense intended to you and the other devs, but I really do feel that there should be an easier way to search / report issues. It would probably save both devs and players time and hassle, as users can easily browse and submit issues, while devs can see which need to be addressed first and fix as many as possible.