I am not sure but I believe, that with this version something has broken with Messenger launched from the sidebar. It's just empty.
For messenger.com, disabling adblocker worked - whole site loaded and it works just fine. So adblocker is blocking something.
I added an exclusion [*.]messenger.com to the Adblocker list, but it does not seem to work for the sidebar app. When I log out from facebook, login page in Messenger sidebar is shown normally, but after login again - the blank page, like it does not load (or block) the content.
I believe, because I've updated the browser yesterday at night, and everything was working up to this point. Not sure if this is the browser's or Messenger's team fault though. Anyone knows about any workaround for that? I do not want to disable the adblocker totally, for rather obvious reason.