Halo: Master Chief Collection Campaign CO-OP is broken

Me and one of my friends recently both purchased Xbox Gamepass Ultimate on our PCs in order to play Halo: Master Chief Collection, however we've only been running around in circles trying to get the darn thing to work in Co-op mode.

So far, what generally happens is that one of us loads in, and then once they finish loading in they get booted and an error saying that they've been disconnected.

We've tried the following troubleshooting:

- Running the game as Administrators

- Running the game in both Xbox Live Server mode and on LAN

- Going into Settings --> Xbox --> Network and clicking "check" and then "fix it". It does seem to always have an issue but once you hit "fix it" it seems to go away, still didn't solve our problem though.

- Changing who hosts the game

The weird thing though is that in Halo: CE, it just flat-out kicks whoever loads fastest out, however in every other Halo game (2, 3, 4, etc.) both players successfully get their loading bars, however only one player's bar says "validating" while the other's will just say "loading". We've left it for upwards of half an hour sometimes and no dice. However, all forge content and such seems to work for lord knows what reason.

We've come to the stupid solution that it's because I'm running the game on an HDD and my friend has it on an SSD that the game can't handle having two people load in at separate speeds...

It'd all be great if split-screen was a thing, but I suppose no one needed a feature that was already coded into the original games anyways.

All that being said, has anyone found a fix or solution to this issue? Surely there's a way to get around this.

Cheers.

:)