Check Password in auth/login issue

In using the default auth/login the an error on 'Step #3 Check Password' and it's returning a value of false.
What is strange is that this was working only two hours ago.
I've also noticed that any of my request over the last 90 minutes to this endpoint are not shown in the Request History.
Aside from verifying I have supplied correct username and password against the correct table and the correct fields with the correct field types what else can I do to debug this?