When you first open the Launcher and the download starts, you should be able to see the version number. Could you let us know what it is?
Also, post your most recent Log files. They should be located here:
C:\Users[USERNAME]\AppData\Local\EpicGamesLauncher\Saved\Logs
I’ve seen this issue only once since the update and the tech here who experienced it was also on Windows 8.1. Rebooting his PC fixed the issue for him but you mentioned that you have already tried that.