I had left the tab open, so I checked the console and there weren't any exceptions, just the output generated from the game being set up. I refreshed the page to test again, and selecting "small" brought up the same puzzle that I previously confirmed the bug with. This time, everything worked as expected though!

I'm using Firefox on Linux which could very well be the culprit here -- I recall an issue with drag and drop that was fixed in a recent changelog. I'll reach out if I run into the issue again.