Yeah that's weird if you don't have the point estimate of an estimator within the interval itself (regardless of the estimator, any estimator will contain its point estimate).

I'm wondering given this wiki site:

Mann
Can you get either the point estimate and standard errors for the actual estimator, or get the n1,n2 values listed in the wiki site.

The reason I suggest this is because if you have a lot of samples, then the normal approximation in the wiki should reflect the statistics and interval generated but if not then you know something is a-miss.

Can you post the entire generated output?