Thanks for the answers, @dklgood, @Jules , @rpegg, that’s right!
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.
This illustrated guide: Tutorial: How to cut without the Crumb Tray (Honeycomb) might be just what you need.
I’m going to close this thread - if the problem reoccurs, go ahead and post a new topic. Thanks for letting us know about this!