SVG / D3 rendering bug when animating

[Dan H]

I'm using D3 (v4) to render a type of bubble chart (x, y, z dimensions).  A 4th dimension is time, so I animate the bubbles from one x,y position to the next. 

The bubbles have bars hanging off each side.

During the animation, once in a while I see some "trails" of pixels where the bars are animating by.  This only happens on certain bubbles/bars and only on some animations.  

Screenshot attached. 

Any thoughts on where to start looking into this bug?  Looks like maybe SVG rendering issue?  Kinda doubt it's from d3 itself?  After it happens, the trail stays there until the next animation moves the bubble/bar, ... but it disappears if I switch away to another browser tab and come back.  Even more evidence of a browser / SVG rendering bug?  Not sure where to look / dig / ask about this next.

Oh - Chrome browser on Windows.  (Does not appear to happen on Edge)

Thanks for any thoughts.