@PC players
I deleted these files:
EDIT: first two seem to not be related to this fix
(installation Folder of H3)\HITMAN3\Retail\HITMAN3.exe
(Installation Folder of H3)\HITMAN3\Launcher.exe
Files in the folders in C:\Users\(Username)\AppData\Roaming\IO Interactive
An let EGS download them again. Note that the third thing will delete local saves and any game settings.
The files get generated on startup again and might have been corrupted.
After this I could connect with my account again. This will not damage progress.
I assume one has to delete less but I went for all three and had success. If someone tries that, please delete file by file and tell us what exactly fixes it.
My assumption the faulty file is the one in this folder:
C:\Users\(Username)\AppData\Roaming\IO Interactive\HITMAN3\TemporaryStorage
Can someone confirm?