No, it's not just Mac version users. I've tried to update a Mac Installation and a Windows installation and get the same result. Download appears to install, program relaunches and says an update is available.
I think the problem arises because the download is Version 18.104.22.168 but the program is expecting 7.5.1.
Some people seem to have reported getting the 7.5.1 update, so there is probably some problem with the servers for some locations, which may not be corrected until after the weekend.
Incidentally, the downloaded update can usually be found in the Folder: C:/Users/'Username'/Appdata/Local/Temp in a Windows System and drive_c/Users/Username/Temp within a Mac.app if you know how to explore the structure of the app.