I work a lot with Pine and it can be a real roller coaster. I think
even the moisture that the glue introduces can add to some movement. If
you are talking about a 4/4 thick top, that sucker will move for ever.
It's just the way it is with pine. I often just pull the sucker flat
with a few extra attachments to the apron and add a shim or two if
needed.

One help is to select boards that are closer to a rift or quarter sawn
cut. Look at the end of the boards and you want to see the rings
running as nearly straight across the thickness of the board as
possible. If you see the center of the log or rings that intersect the
same face twice, ie like a smile, fhugetaboutit. That sucker will curl
up like a potato chip.

You can alwas re-rip the panel and reglue it to help flatten it but
depending on the severity of the cup you might just have to rip out the
piece entirely and glue in a new one.

Finally, use quartersawn White Oak next time and you'll get a flat
panel that stays that way.