Pools of four produce ties constantly in pickleball, because there are only three games per team and no draws. Three teams on two wins each is the normal outcome, not the exception, and the order you separate them in decides who reaches the playoff.
The standard hierarchy is head-to-head first when only two teams are level, then point differential, then points conceded. Where it goes wrong is the three-way tie, because head-to-head is circular by definition — each team beat one of the others — so it resolves nothing and you fall through to differential whether you planned to or not.
Publish the full hierarchy with the draw, including what happens on a three-way tie, before the first serve. Tournamyx recomputes the pool tables on every saved result and applies the same rules every time, so what players see on the public link mid-morning is the same logic that decides the bracket at lunch.