Hello Rogier,
I have tested the Storefront theme, version 4.6.1, with the latest of Fluid Checkout and could not replicate any of the issues you mentioned.
It is likely that this error is a conflict between plugins, so it would be helpful if you could run a plugin conflict test to find out which plugin or theme might be conflicting with Fluid Checkout.
Basically, you temporarily deactivate all plugins except for WooCommerce and Fluid Checkout, then re-activate each plugin one by one until you find one that causes the issue. Ideally this should be done in a test/staging copy of your website. You can find more specific instructions in the article below from WooCommerce:
https://docs.woocommerce.com/document/how-to-test-for-conflicts/
Once we know what plugin or theme is causing this compatibility issue with Fluid Checkout, then we can work on fixing it.
Kind regards,
Luiggi
Hi @metaphysics ,
This ticket is being closed due to inactivity. If you need further assistance related to this issue, simply reply to this message to re-open it.
Kind regards,
Diego.