I added cherries to a batch of cider today. I hadn’t seen a single bubble in over a week. No joke, within 5 minutes of me resealing the fermenter, it was bubbling like mad! How is that even possible?
Even if the yeast started on the cherries immediately, wouldn’t some pressure have to have built up to fill the headspace again?
More likely is that the cherries acted as nucleation sites triggering a de-gassing event. Can happen with hops going into an active fermentation as well.