The new layer options for the OnParticleCollision trigger introduced in build 876 makes existing worlds' layer options set to 'Nothing' instead of 'Everything' by default. This is evident in-game in one of my worlds (https://vrchat.com/home/launch?worldId=wrld_0401e2e8-9693-4115-afca-c58827436da8) and is apparent when loading the same scene with the new SDK.