In SDK 3.8.1, multi-platform building is broken and stops responding. It stops at 25% and never continues, spitting out the error "ArgumentOutOfRangeException: Index was out of range. Must be a non-negative and less than the size of the collection."

I have tested this with VRCFury on and off the avatar as well. I do have EasyQuestSwitch, but this has not affected anything when uploading before the per-platform override was added. My world uploads fine with it, so I can deduct that it is not an issue