I'm using Kibana 6.2.4 and there is a little annoying bug. Here is a picture showing my histogram with no problem :
When I move my mouse over some points, it shows a circle around the point and a pannel with some infos about the data. Until then, it's OK. The bug appears when I mouse my mouse away from a point. It's not with every point tho. Check the picture below with the visual glitch (I made a yellow circle around the glitches) :
The glitches disapear if I simply switch the tab in my browser and come back to kibana. I have no bug with google chrome.