C2 Drag behavior may not work correctly in Web-Component

I've put canvas of C2 inside a web-component tag in html and import the c2runtime js as a utility library for this web-component.. Everything may work correctly but the drag behavior for the sprites may not working correct. You can touch but cannot drag element.

with normal html div and canvas, the drag behavior is working perfect as expected.. ??

My question is why and how to fix it up

Best regard for all experts.

Thank for all of your help

HoangAnh