Skim coated paneling now cracking after a year. Would eave vents help?

My kitchen had paneling along the outside. wall with a 1'x1' box over the sink. I guess you would call that an eave.
I skim coated and taped the corners. I taped some of the seems other's I did not.
It looked great for about 8 months until this winter and then started to crack along all the joints.
I know what needs to be done. Screw in the corner and tape the joints.
But I suspect that it is really cold behind the eave.
Would vents help keep the heat a constant and reduce cracking.

I believe the wood paneling is contracting with the change in humidity.

DougB has it rigth- wood is hygroscopic and both adsorbs & releases moisture much more slowly than plaster or drywall muds.