I have a two story house - 3250 sqft with 1400 ft2 upstairs and 1850ft2 down with two AC units, 3.5 Ton downstairs and a 2 Ton for the updstairs. I have 3 bedrooms, two bath rooms, a media room and game room upstairs and recently had a zoned evaporator installed to separate the media room from the rest of the upstairs for cooling when the projector is on.
My problem is the humidity stays around 60-65% relative upstairs and it feels uncomfortable when watching a movie. I would think the ac(2ton) is undersized but the house is fairly efficient with radiant barrior in the attic. The unit has no problem cooling the upstairs to 73(usual temp) even when it's 97 outside but the humidity seems to stay high.
Downstairs is a different story, humidity is usually around 50 - 53% measured with the same hygrometer and it also has no trouble cooling. The downstairs unit seems to cycle for shorter periods and more often than upstairs but the humidity is always at least 10% lower.
I've looked for leaks in the returns(I have three upstairs one origianal in the hall by thermostat #1 and two 12x12 - one in media rm and other in daughters rm.) The evaporator is draining and can seen a good bit of water traveling through the pvc pipe heading to the drains in my bathrooms. No water in the emergency pan.
What can I do to fix this problem? I'm about ready to install a different unit even though I just installed this new zoned evaporator.

Typical reason for high humidity is that the unit cools too fast and as such, the relative humidity goes up because water is not removed. For humidity removal, it is actually better to have a smaller unit. A dehumidfier may help.

Do you turn the zone off when media room isn't being used? With the zone closed, the upstairs might have to short of a run time.