Sometimes the fireballs used to burn chains between players linger in the Kabal boss fight of MSP. These remaining fireballs are simply the visual effects though and cannot be used to burn chains. These can stack up and it becomes very difficult to tell which ones are real.
I do not know the exact replication steps for making this happen, other than running the Kabal boss fight normally. It isn't the most common bug from what I have seen, but it showed up as the same time as the
Demogorgon portals issue, and appears to be related.
Also, Kabal never seems to chain players together if there are only two in the boss room, which seems odd.
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Signature [WIP] - tyvm John