Plugin is not working

Hi,

I just installed the Fluent forms plugin but it’s not working as expected. When I navigate to fluent forms page it’s saying “Something went wrong, please try again.” I tried deactivating all plugins, reinstalling WordPress core files but none of them worked. when I view the console I can see the following errors.

GET wp-admin/admin-ajax.php?fluent_forms_admin_nonce=f80640061f&action=fluentform_get_post_types&_fs_blog_admin=true 400 (Bad Request)

I guess the web hosting firewall is blocking admin-ajax but not 100% sure. what could be the possible cause of this issue? please kindly help.

Thanks