Turns out that at certain browser zoom levels, the two additional columns of the variable table are hidden entirely from view, and line up perfectly with the "Linear vs Grid" buttons, visually suggesting that there is no more data. The only clue is a scroll bar which in Chrome is easy to miss.

I'm visually impaired, hence I've been struggling with this for over two hours. Them's the breaks when a billion dollar company doesn't a11y test their UI, I guess.