Richselect Component can't be selected in smart mobilephone

I have a problem with using ‘Richselect’ in my page.
The Richselect has 15 items,The latter part of items can’t be selected in smart mobilephone.

However it works correctly in my computer’s Google Chrome browser.

I think the conflict lies in the popup window can’t be focused.

Any hints?

Not quite sure what is the reason of the problem - richlist can have inner scroll, and as result you can place long list on the small screen of smartphone

If issue still occurs - please provide any kind of demo , where issue can be reconstructed.