I think the indicator area (or the panel) is failing to scale icons.
For this example, the panel was configured to 100 px size, and Plank icon size was set 100 px too, Plank has the correct size, the Clementine icon at the panel stays at 64 px or some number near that, and the rest of the icons don't scale:
and now 24 px :
Plank scaling works but the icons on the panel are not scaling correctly, they are "cut" as you decrease the panel size. For this example the numix-icon-theme was used, but it happens with other icon sets.