Crystal, is it possible your bottle has become contaminated with something? Or your brush or applicator?
I've never liked using pledge because I worry about how easy it is to remove (with alcohol, ammonia or even just hot soapy water, I've found).
I prefer what is now called Rustoleum Elite Diamond Varathane - water-based wood sealer. You can usually find it at hardware stores in quarts or half-gallons (and that's expensive) but it lasts and lasts and lasts forever. Amazon retailers sell smaller quantities, as does Polymer Clay Express.
Minwax also sells a water-based polyurethane that works with clay, and Kelly-Moore Paint stores have a product called Kelthane that works perfectly well (their stores are all west of the Mississippi, I think).