Without a test project, I am afraid that there is not much that we can do. In case Erik provides us with one, I will make sure that we post the solution here as well.
In the meantime, could you please make sure you are using the latest version of the Prometheus controls? Could you additionally send us a screenshot of problem? I would as well ask you to take a few minutes to try to reproduce the problem with our Server Side API
the Telerik team