For the last couple weeks, it seems RD Tabs Update was directing users to download 2.1.19 as the latest release. Of course, 2.1.20 is the latest release. This has been fixed. When I changed to my new (faster!) server, I accidentally uploaded an older version of the online portion of the update app.

Just a side note, 2.2 is still being worked on, but I've been swamped lately and haven't had time to dedicate to it.