I'm not sure if this is WAD or a bug, but I thought I'd report it nonetheless.

Ah ok - is this something that is a roadmap item of yours perhaps? Or is it just not possible given how Blizzard has designed things?

It's not impossible but it would require a redesign of the personal resource widget as it isn't meant to handle bars filling up. It only deals with hiding and showing textures based on resource.

And even then I don't feel like a bar style resource would work as well in that widget. It would almost be better to do something like this with weakauras.

Gotcha, thanks for the info! :)

This is working as intended as it follows how the blizzard personal resource on target works.