Glass fursuit eyes bubbling issue.

I've commissioned an absolutely amazing artist for a fursuit head, but for some reason every set of eyes painted installed seem to be horrifically bubbling between the blanks shortly after being installed.

These are the eyes when installed - Note the distinctive lack of bubbles:



Then within a day of being installed- this happens:


Now, she's tried glass eyes, resin eyes and even a hybrid of half glass-half resin using a variety of glues but it keeps persisting.

Does anyone know why?