Cast Iron Skillet Loses Seasoning After Cooking Chicken?
Seasoning in cast iron pans is very sensitive to acidity.
For example, tomatoes or a sauce based on it, will easily degrade your seasoning.
It is possible that your chicken, its marinade or exterior is acidic as well.

Make sure also you cook the chicken on its side long enough for it to naturally come off and no longer stick to the pan surface. Don't force it off.