Thank you for bringing this issue to our attention. It is logged, and you can expect a fix in a future release of Kendo UI.
Meanwhile, as a workaround, I can suggest disabling the TabStrip's animations via the animation option
, as they seem to be causing the issue, e.g.:
I am sorry for any inconvenience this might cause.
I have updated your Telerik points as a token of gratitude for helping us improve the quality of our product.
Telerik by Progress