Thank you for writing.
I am not able to reproduce the issue you have described. I would kindly ask you to open a support thread where you can provide me with your project or a sample one, where the issue you have described can be reproduced. This will allow us to investigate it and provide you adequate support. If you are not able to prepare a sample project I would need more information on your case, like how you setup your multi column combo box, what events you have subscribed for, when and how you add rows to it and anything else you think might be related to the issue.
I am looking forward to your reply.
the Telerik team