problem firing specific float glass coloured powderd glass with bronze inclusion

Hi everybody.

I would appreciate any help and comments to the following problem I face.  I fire 2 layers of 3mm float  coloured with 1045 Optul glass (cherry red - Lead free powdered glass) and bronze inclusion.  The glass is not coloured throughout.  I have fired this same small dish for approx. 4 years without a problem and with excellent results.  During the past few months, air is trapped within the glass where there is no powder or inclusion and it becomes foggy.  I tried to include a bubble squeeze to eliminate air trapped in the glass. Less air was trapped but the fog was still there.  Anybody has any clue to how I can fix this?