I've just updated to version 3.1.5 and noticed that various node icons are no longer appearing in the editor. For example the Aedes MQTT broker node is now not showing any icon in the editor view - but it does show the icon properly in the pallette and in the node editor.
Could this be related to PR 4491 ? I've noticed now two nodes which are not showing icons in the editor.
if it helps, the aedes icon image size is 272 x 272 (png), that would reduce the scalefactor by 20 / 272 = 0.07352941176470588 - don't know the code to know whether that would be a problem.
Edit: my mistake, the width isn't the full image width see the line above