dhtmlxTree with mobile device

We have dhtmlxTree display in iOS & Android mobile device through Chrome.
Somehow dhtmlxTree display the tree content but can’t scroll the content up & down with the vertical scroll bar. I found the scroll bar did display on my PC’s IE and Chrome, but why not showing in mobile device? Please advise. Thanks!

there is not scroll bars in mobile browsers.

It is possible to scroll on both Android and iOS. iOS shows scroll while scrolling, but scrolling is finished, the scroll disappears.

How to fix this?

This is not a bug. This is standard behavior for all mobile os.