It is the normal range for past Nevada Democratic caucuses, but your question is valid since early voting was allowed this time.
You would think early voting would mean most Democrats would want to participate—excellent question the mass media is not discussing.
New data tidbit—16% of black voters voted for Steyer—which means they were more susceptible to billionaire ads.
Those are voters who probably would have voted for Biden.
In South Carolina that will really hurt Biden, and could cost him a victory in the state.