Tank health bars can be obscured by enemies

[Nomad7]

Champion health displays as a red bar near their feet, but when enemies approach (specifically melee enemies) they can get close enough to obscure the health bar.

Steps to reproduce:

1. Launch idle champions and proceed to an adventure with melee enemies (for example Mad Wizard zone 7)
2. Allow melee enemies to engage the champion(s) at the front of the formation
3. Observe the champion health bar

Expected results:
Health should remain visible

Actual results:
Some (or all, in cases of larger enemies) of the health bar is obscured.

Notes:
Most enemies don't completely obscure the health bar, but more enemies generally makes it harder to see, and larger enemies (even the bears on Mad Wizard z7 which aren't especially huge) tend to cover up at least the upper half.
Some bosses (like the z40 Juggernaut) also caused this problem, and have been fixed (Juggernaut in v177, Owlbear in v210).