I believe that the value of limitStreamViewersMaxViewers is only utilized if there is no specific limit for the given stream. When a new connection is initiated, it checks to see if that stream has a specific number associated (i.e. myStream=20) and compares the current count to that value. If that does not exist, it will use the default value as specified by the limitStreamViewersMaxViewers property.
If you are seeing a problem within that workflow, please zip up your conf/ and logs/ and send them to
firstname.lastname@example.org and reference this post for further review.