I was using this demo
to test the orientation. However, I tried the one you use, and it also worked as expected, even if I put everything inside another PageView, as you specified earlier.
Perhaps you are using some other styles, that may reflect on the TabStrip and PageView. In order to troubleshoot the problem further, please open a support ticket and attach a simplified sample project which reproduces the behavior, so that we can investigate it locally.
the Telerik team
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