Those are the normal group overhead icons, and you can call thm 3d or whatever. But harvestmap actually does no 3d icons it just does 2d and makes them turn with your view angle. If you go to the icns above a harvest node and runa round it you'll notice it
So the naming is nothing here, and does not tell you it would be the same technic or API or code used.
Harvestmap definately uses it's own created controls but that companion icons and group icons is ZOs code and technics.
2 totally different things
Try to disable things like the minimap you use or addons thathave to do with companions or groups and test if this fixes it, as these coud interfere with the icons above your head (just like Ody could too).