I am trying to enable the OTP password flow on my single page application. With the intention of using the code via email connection method. However I can not enable the grant and it is greyed out. There is reference to setting token_endpoint_authentication_method to something other than none, but I can not find this setting anywhere.
Regarding the greyed-out OTP Password Flow grant for the SPA, it is expected that all applications of the public type will have this option greyed out due to security concerns. You can read more about that here → Customize Email Handling.