One follow-up that arrived on !60 minutes after v1.2.12 was tagged, and belongs with it.

• 🔢 An empty or zero progression step can no longer be saved. With a progression rule on,
  leaving the step field empty or at 0 marks it red, explains why, and holds the save — a step
  that cannot progress anything is no longer stored by accident. Nothing else changed; a
  self-hosted instance only needs the new web bundle. (mflova, !60)