Thanks for any help.

Where were they air dried, and where have they since you glued them together? If they were air-dried outdoors, in an unheated shed or garage, or in a damp basement then they would still have had a fairly high moisture content, regardless of how long they'd been sitting around.

When you had them "laying flat with weight on them," were they laying on a table or other flat surface so that only the top surface was exposed to air? This would cause moisture changes to be more extreme on one side than the other, which would cause cupping.

Were the pieces flat-sawn, quarter-sawn, rift sawn? Some cuts are more stable than others. Were they glued up with the orientations of the annual rings alternating or all facing the same direction?

The most conservative thing you can do is prop up the piece so that air can circulate over both sides, and leave it for several weeks. If that doesn't fix the problem to your satisfaction, you're left with cutting it up, re-flattening and re-assembling it.