IanM Do you by any chance have the dev version of it installed via composer?
Really sorry, no idea. I just run composer update -W --prefer-dist --no-dev -a on rc3 then composer require flarum/audit:"*".
IanM try the latest version of fof/geoip
Got the latest fof/geoip 2.0.0-beta.9
Edit: Tried reinstall Audit with composer require flarum/audit, still the same.