Apply this behavior to any Particle System object to force it to update with Timeflow.
Right-click an object in the Timeflow view and select:
Add Tool > Particle System Update
By default, a Particle System only updates in edit mode when the game object is selected. To make the particle simulate whenever Timeflow is played, add this component to the object.
Note that particles only update when playing Timeflow and not when manually setting the current time or dragging the playhead.