This could be down to a number of reasons:
- The cider may not have been stirred enough at point of flavour addition; this is essential for ensuring sufficient yeast is transfer into the bottle for secondary fermentation (bottle conditioning).
- Finings may have been added prior to bottling. Finings are usually included within the kit and should be used for kegging only – use for bottling will prevent carbonation (some homebrewers have used the finings to get a clear cider, which isn’t necessary as it will clean naturally in the bottle over time).
- It’s also possible that that the bottles have not been left long enough, sometimes the cider can take 3-4 weeks to fully condition.