This module can't be used in conjunction with fluent apparently.
I checked the database. Fields are only added to SiteTree and not to SiteTree localised tables. So data isn't saved to the db.
I've created a hacky fix that allows the SEO fields to be saved to the localised tables, PR and fork are here if anyone needs them until this is sorted: https://github.com/SilverStripers/seo/pull/24
This module can't be used in conjunction with fluent apparently. I checked the database. Fields are only added to SiteTree and not to SiteTree localised tables. So data isn't saved to the db.