Uncategorized conferences are completed conferences that contain no conference statistics.
The majority of uncategorized conferences happen when a single userJoined event occurs, without receiving any other events or statistics.
An uncategorized conference may also occur when certain browser versions fail to fire ICE-related events and the internal callstats.js state machine does not move forward. This usually happens when fabricSetup events are not detected, therefore statistics are not polled.
Uncategorized conferences are not the same thing as failed conferences.
You can verify the implementation of WebRTC getStats across browsers using our handy free tool, Verify.