Minecraft Realms (PC) "Invalid session - Please try restarting Minecraft"

When I click "Minecraft Realms" from the main screen of Minecraft, it shows me an error and does not even allow me to see my world options. Restarting the game does not help, and neither does logging out completely. I've even reinstalled the game. This issue has always been an occasional issue, but the past few days it hasn't gone away at all.