Short update: I recently encountered the exact same bug on a 3D scatterplot with transparent color_line. I’m surprised I seem to be the only one struggling with that, as it seems like a pretty big bug 
Any idea on how to fix this is very welcome!
EDIT : for the 3D scatter plot, I managed to solve the issue by not specifying an array of sizes for the points. It seems however that there’s a bug, as I don’t understand why individual point size should relate to perspective.
