During colonisation, compare bags from the same batch at the same age. Note the progress of mycelium, stalled areas, damage to packaging and abnormal colour. Keep questionable bags out of routine opening or handling; follow your containment procedure and obtain advice. Opening a suspect bag to smell it spreads material and exposes the operator without reliably identifying the cause.
When the bag is ready, follow the opening and fruiting method for that species. Light, air exchange and moisture management must work together. Long stems or small caps are reasons to inspect crop identity, light and air distribution, not proof of a single cause. Dry margins near a fan and persistently wet clusters elsewhere can coexist in one room; raising the room's humidity setting alone may not solve that distribution problem.