Please, find attached a sample page based on the scenario you describe. You can see an alert showing the number of docks in the static zone at Button Click handler and SaveDockLayout handler. How do you check what is the number of docks in the static RadDockZone on your side? I would like to ask you take a look at the sample page and let me know whether I am missing something.
In case the attached page cannot help you solve the problem, please, open a support ticket and send us your test page which reproduces the issue so that we can take a closer look at your code. We will be glad to help you.
the Telerik team