Actually it doesn't update in the tree view but the icons DO show in the select node search window when adding...
I am also not getting it to work? Any help please?
Yes, this is happening to me too, but as @Zoidberg said, I can see the right icons when trying to add the nodes...In my opinion, it's not a big deal, so I'll go ahead
I have tried to update my previous reply, the web won't let me.
Reopening Godot solved the issue for me, the icons are now where they are supossed to be.. Cheers!
Same issue with Godot 3.2.3 (mono version), the editor must be restarted to see the icon change