Hello,
If you have confirmed that all payment settings are correctly configured, Disable all third-party plugins not related to the theme and check the issue.
If the issue is resolved, re-enable plugins one by one to find the conflicting one.
If the issue remains, Could you please check once how it works with some default WordPress themes like TwentyTwenty Five or WooCommerce Storefront to understand if it is our theme issue or not?
If switching to Storefront resolved the issue, it might be theme-related. Then, share WP admin access so I can investigate further.
Best Regards,