Oh no, I’m sorry to hear you’ve hit a snag.
You can print on objects up to 2" thick by removing the crumb tray. However, your Glowforge can’t focus too far down, so you may need to put something laser-compatible underneath your material to lift it up. Raise it until the top surface of your material is between 1.5" and 2" (50 mm) high, measured from the metal plate on the bottom.
Our community has developed some great Tips and Tricks, and this illustrated guide might be just what you need.
Since this problem is being seen on materials that were purchased from another company, we can’t offer support for prints that don’t come out as expected. Materials may vary widely from piece to piece, even if they’re created by the same manufacturer.
I’m going to move it to Beyond the Manual so other folks here can help. Should this happen with a print on Proofgrade materials, please open a new ticket in Problems and Support and we’ll help you right away!