Hi there, I am having the same issue after I install the webMethods Mediator version 9.12 and I wonder if you could share the solution you found for this issue. Pls, advise.
I found the solution. The sw license keys provided to me did not have permissions to configure the Messaging configuration, so this explains the issue. It would have been nice if the option to configure the Messaging would have been greyed out or removed based on what the sw license allows, so we would not be lead (or misled) to believe the feature was corrupted. Next time, check the license key more thoroughly before!