Our small deployment was accidentally sabotaged by the beta opt-out migration, see T260353. Most users (a group of 600k) have been seeing opted-out behavior and the legacy conflict workflow, even on the small default wikis. A graph of how many conflicts use the new workflow shows that our first deployment on March 25th didn't make much of a difference on the overall proportion of people using the feature:

We need to remove the problematic opt-out migration, and probably clear all full default opt-out preferences, after communicating with users. This change will begin our real "small default" phase.