By mistake I launched the 4.21 install file instead of the latest 4.23, and Plus! informed me that version 4.21 wasn't compatible with the installed version of Messenger (I'm using the latest WLM 8.5 beta), so Plus! asked if it should download a compatible version of Plus!.
Although I already have the installation file of 4.23 I pressed Yes and it began downloading
To my big surprise the downloaded version of plus! was 3.63? I'm guessing it should have downloaded 4.23.276?