By Official HCS -
As we mentioned last week, the team has been working on a hotfix for party joinability, and this fix is now available via a content update to Halo: The Master Chief Collection. Largely, this update will revert to the same party functionality that was available prior to our 4.21 update, and specifically addresses joinability issues that players with large friends lists have been experiencing.
As of this time, this weekend’s ESL online cup #1 remains on schedule, and the HCS staff at 343 and ESL are currently working with teams and players to verify that the joinability issues have been resolved to ensure that things will run smoothly during the tournament.
Thanks for your patience and best of luck to all competitors.
Franchise Media Director