OTP doesn’t work with Ultimate Member Registration Form

Hi support team, I have followed the instructions, creating the registration form and have phone verification enabled for Ultimate Member Registration in OTP verification setting. After I fill in all information and click on “register”， the user was successfully registered but I didn’t get any OTP page to verify the code and of course, my cell didn’t receive any code. I am running the latest release of the ultimate member and OTP verification plugin… could be an issue related to the theme? Any suggestion would be appreciated!