Help me understand this

[GibsonGM]

How long was it out in the elements?

One thing I'm noting is the glazing is a bit rough where it meets the glass. I wouldn't allow that in my work. Just being picky.

Is the glazing painted? If not, moisture could be penetrating it, and going right under your paint, into the wood, and essentially pushing the paint off. Otherwise, the paint, for whatever reason, did not prevent moisture wicking, and has allowed moisture to migrate under it. That's my 'judgement'.

Remove, allow to dry, re-sand, re-prime, topcoat twice again, ensuring the glazing is painted right to the glass (no primer on the glazing).