Game and Plater version
Plater-v564.2-Retail - DFv468 - 10.1.7

Describe the bug
Recently (sometime during Season 2) buff special icons will randomly show up in the center of the nameplate instead of the set location (in my case to the right of nameplate). Was always pretty inconsistent on when it would happen but I noticed it happens basically every time in the mage tower healer instance with the Corrupted Risen Mage buff.

Screenshots
The issue:

My buff special settings:

It's happening with enemy NPCs

Is that a friendly or hostile unit?

Please provide some screenshots of the Enemy NPC, Friendly NPC, Advanced and Level & Strata tabs as well please.

It is. They likely count as "friendly nameplates" on blizzards end and inherit the "friendly box selection space" setting from the advanced tab.
As the Buff Special area is anchored to the unitFrame directly, this directly translates to the close anchor.
Might need to check if it can be safely re-anchored. As a workaround: increase friendly box selection space width a bit.

Are those units fully "clickable" on the whole health-bar size?

When the buff icon appears in the middle, the area to the right of the buff is not clickable (and doesn't show hover highlight either). Normally I can click the whole healthbar. Screenshot showing lack of hover highlight:

I'm beginning to wonder if it has to do with the units transitioning from not attack-able to attack-able. In the screenshot below, you can see each enemy starts as not attack-able. They then slowly "activate" in waves. Wondering if this is why I can replicate the issue so easily in this scenario but not in the open world.