This could very likely be due to the use of 1 or more wrong keywords in the configured message. 


The keyword for inserting the actual OTP should be user.otp. 


When any wrong keyword is used in the message configuration an error is raised and the system just returns a predefined static message because the system does not know what it should put in place of the wrong keyword. The static text which you received is the fallback mechanism provided to avoid any configuration errors resulting in users not getting any message at all. The fallback message will ensure that the user will at least get the basic OTP to continue with the login.


Please check the customized message configuration to make sure that all the keywords used are valid and correct.


NOTE : Keywords are the dynamic parts of the message placed between the tags : <%=     %>