Coated tablets Defect

We are facing peel off defect in seal coated tablets of Vildagliptin 50 mg+ Metformin 1000 mg, during preheating of seal coated tablets prior to start the color coat spray,
what was the reason for peel off defect?


qty of plasticizer may b low

Already 7 batches (03 Lot each) coating has been done, this type of observation was not seen earlier. in this particular batch 01 Lot coating was done, and no such type observation was observed,
if qty. of plasticizer is low than such type observation observed in other batches.

can share defected tabs pic?