I have a cider I put on CO2 a bit over a month ago in my kegerator, its on about 13psi and the temp is about 35-40. I am able to pour a fizzy beverage but it quickly looses its fizz and is quite flop. The beer I have under the same pressure is is quite fizzy. Air relief on the cider works fine and releases with a whoosh just like the other beer I have. Not a new keg and I have already checked for leaks.
I have the flu and I am not running on all 4, so sorry for the scatterbrained post.