I assume the dynamic panel you are referring is the “16 colors” overlay. This works just fine for me in Win 10 + Chrome, after clicking on any of the “16 colors” text. I can drag up/down to move the list of color swatches, no page scrolling.
If I load your URL into Safari on iOS phone it does trigger both the onDrag of the dynamic panel (for a very brief time) and the drag behavior for the browser/page (scrolling). In general, I haven’t had issues with this in my prototypes with draggable panels. I usually use the Axure Share app, but I loaded a few of my prototypes in Safari and they behaved the same. Dragging to scroll panels works fine. If the panel is initially dragged “the wrong direction” (i.e, dragging down when the panel content is already at top and can’t be dragged down any further) then it triggers the browser drag, but once the panel content moves, it behaves properly regardless of drag direction or “over-drag” (dragging beyond panel area.)
I’m curious if you have these in a repeater and if that might have something to do with the unexpected behavior. Any way you could post your .rp file or a functional facsimile of it?
I also wonder if turning on the “Prevent vertical scrolling (blocks elastic scrolling)” option in the HTML generator–Mobile/Device tab would help this.