Hi @Ary824,
There is a bug in previous version of launcher where some internal information stored encrypted in a cache hidden inside AppData\Local\Epic\ then loads of numbered files.
The only was is to remove the Windows Application Uninstall
BOTH of these must be uninstalled to allow a clean new installation of Epic Games Launcher downloaded and installed.
This problem was the same in 5.3 and fixed by doing an uninstall / new install as above