Will a 1/2 full keg take longer to force carb compared to a full keg? I have had it at 30 psi for a couple of days and not sure what is going on. Pours very fast. Is it because it's cider?
What temp is your keg sitting at?
Did you release the pressure relief valve on the keg prior to pouring? If not (and you say your cider is pouring very fast) the fast pour from excessive pressure could be knocking a lot of CO2 out of solution causing the cider to be less carbonated than desired.
Try pulling the PRV ring to reduce headspace pressure, then turn up your gas pressure to serving levels and then try pouring a glass. Should fix it.
Post back if not...