3D models invisible all of a sudden?

  • I'm honestly guessing the solution to this is probably something simple and it's just a setting I clicked by accident, but suddenly any 3D models I drag onto the canvas from the materials palette are showing up invisible and I can't figure out why. It was working fine last time I used the program a few days ago.

    Like, the models are there, I can click on parts of them and drag them around, but they're just completely transparent. I tried filling in the background canvas with color just to make sure they didn't turn white, but nope, they're just totally invisible. Other materials, like patterns, seem to work fine; it's just the 3D models.

    Has anyone else encountered this or does anyone have any guesses on how to fix it? I tried restarting the program and the computer, obviously, as well as making sure the software was updated, and nothing changed. Any help would be appreciated.