Thanks for letting us know about this. I extracted the logs to investigate, and it looks like the material was too thin for the Glowforge to focus.
The objects you use can be up to 2" thick. If you remove the crumb tray, you may need to put something laser-compatible underneath your material to raise it up so that your Glowforge can focus on your material. For best results, the top of your material should be between 1.5" and 2" high, measured from the metal plate on the bottom.
The community online has developed some great Tips and Tricks information, and this illustrated guide looks like it might be just what you need: Tutorial: How to cut without the Crumb Tray (Honeycomb)
Can you let us know if you are still having trouble?