When wood is exposed to high humidity, it expands. If the relative humidity is +60% above or below the wood, expect expansion. If the dew point of the air in the room is near the temperature of the slab, expect condensation on top of the plastic under the floor. The warpping would continue. Get a relative humidity meter and measure the %RH in the room and under the floor. Keep the %RH at about 50% above and below the floor. If the floor is over a crawlspace, check for<60%RH in the crawlspace. If the crawlspace is +60%RH, cover the earth with heavy plastic, close the outdoor vents, and dehumidify if necessary to <50%RH.