We found a bug in our application on tablet portrait mode when we want to select a date from the filter menu inbuilt feature of Kendo grid. 
When the user wants to select a date, the filter closes up and the user is not able to select any date from the calendar.

The issue is happening on tablet device in portrait mode and we found out that it's happening on your documentation too. To reproduce the issue, please go to the "Angular Grid Filter Menu" in your documentation:
https://www.telerik.com/kendo-angular-ui/components/grid/filtering/filter-menu/

Please open the dev tools and set the browser on any tablet portrait size or use Galaxy Tab S4.
In your first example (Angular Grid Filter Menu), please click on the "Date" filter in the grid. When the popup opens up, please click on the calendar icon 
of the date input field. 
When the calendar shows up, try to select any date. You'll see that the filter closes up and the user is not able to select any date. Demo video attached for reference.
Please fix this bug as we support Samsung Galaxy tablet devices and we're using this feature in our project.