Just a note to say that what ever you are doing at 675C, you are not annealing. That is a bubble squeeze temperature. It seems to me you are letting all the substance of the glass equalise to the 675C temperature before you go to the annealing soak and then on to the anneal cool.
675C is above the upper strain point of both Spectrum and Bullseye, so no annealing can occur at that temperature.
Perhaps if you describe (if you want to) what this soak at 675 cured, we could figure out what is being achieved.