It was a clear glass out of the kiln, the 20x5 recipe. First, it would be helpful to look at the cloudy areas under a good microscope. Is it happening on the surface, under the surface or at the glaze:body interface. If the latter, the glaze chemistry could give clues about whether it is likely to be vulnerable to leaching (and thus a surface issue). In this case, the cloudy areas are occurring where the glaze is thicker (around the handle join). Perhaps the body is waterlogging and the water is migrating up into bubble networks and making them visible.
Clouding in Transparent Glazes