In this case I'd make sure all my downloaded 3rd party content was moved out of the installation directory and try redownloading and installing the F3 mod.
Failing that with all 3rd party content saved elsewhere I'd delete all local content through Steam, restart machine and then reinstall AC.
Someone may be able to assist with less drastic measures but this worked for me last time I had issue with AC
Failing that with all 3rd party content saved elsewhere I'd delete all local content through Steam, restart machine and then reinstall AC.
Someone may be able to assist with less drastic measures but this worked for me last time I had issue with AC