Thinsulate is basically fiberfill batting, so there is air movement THROUGH the material. That will bring moisture which will condense on something cold. Foil and bubble wrap are impervious, there's no air moving throgh them, so no moisture, no condensation. You could foil or plastic wrap the thinsulate, or buy a new sheet of bubble wrap.
That you're getting condensation might also mean the gasket
on the box is leaking air. The usual test for that is to close the "door" with a fresh dollar bill across the gasket
. if you can easily pull the bill out, the gasket isn't seating tight. Sometimes a little ArmorAll will soften it up and get a better seal, sometimes it needs replacing.