Why does dvc checkout files, then delete them?

It looked like my files in data were going to be restored from the cache. I checked periodically as the checkout command ran. When it completed, the data folder had been removed.

For Future People™ who may arrive here. My drive was filling up, and checkout was backing out the files it could check out. The error message asked if my cache was up to date, and didn’t allude to my drive filling up.