I presume the fix for the health/mana not showing on the main player frame has made it where the pet's health/mana always shows up regardless if the checkbox is turned off.

I'll fix it for the next version (2-3 days)

Blizzard fixed their Interface Code, and also added the Health/Manabar Left/Right fontstrings

I fixed it for the next version. See 00e84b6 if you want it now.