Air got sucked past the IFP. It's not a totally awful thing to fix if you've worked on suspension, but it is miserable to get 0% air mixed in the oil. 1% is easily attainable.
Remove the actuator, and unscrew it from the base of the post. Internal/external design is slightly different, but the cartridges are the same once removed. Get the cartridge out of the post, and hold it in an appropriate shaft clamp. Remove the bottom of the assembly with a pin spanner. Dump the oil out into a container. Remove the sliding shaft with the damping head on it. Push the air piston out of the seat stanchion, if everything didn't come out when you removed the cartridge, then remove the IFP. Clean parts, then prep for reassembly: Slide the air seal head (the part with the air valve) into the air/oil chamber; push the IFP onto a 10mm socket/some other chamfered thing with a 10mm outside diameter; place this up against the air/oil chamber that you prepared, then slide it on (goal: the quad seal on the inside is too tight to push straight onto the unchamfered chamber, so you must put it on with an assembly guide, or you WILL damage it). Install this prepped part into the seatpost stanchion, and leave the IFP just at the top of the air/oil chamber. Fill the tube to the top with the oil you removed--up to the top of the threaded portion of the stanchion with 5wt reverb oil (shops have tons of this stuff...). Miserable part coming up: place the threaded bottom of the cartridge on the damper rod, holding it out of the way. SLOWLY insert the damper head, noting the purging of air/oil. This will be messy, and probably shoot oil all over you/your workspace. Once the seal head is in the air/oil chamber, thread the bottom of the cartridge on, then tighten.
Pump the cartridge up to whatever it's supposed to be at (200ish PSI), then check for squish. If it is gone, you are finished, and can reassemble the rest of the post.
Work in a tub/bucket that can hold the whole cartridge assembly. Anyone who works on suspension can fix it, but it's a sucky job. If you can wait, send it back to KS.