Mounting Resistance expiring?

[Ordo.Lupus]

Description of Bug Experienced:
I've had a few characters (all earthkin) where I've spiced them with 4 levels of EKD. And I've experienced on several occasions that the +3 regen mysteriously expires after sometimes 5 minutes but also after 30 minutes of having activated the stance. I can't tell if it is dependent on the Temp HP from stance or what else might cause it. The ac, ab, uni save bonus all persists and it's only the regen that goes *poof*

Steps to reproduce the Bug:
Earthkin race with Con 15
4 levels of EDK
Pick iron stance + mounting resistance 1
activate Defensive stance
(lose all temp HP to damage?)
wait 10-15 min

Expected Result:
Mounting Resistance passive regen persists during Defensive stance

Actual Result:
Mounting Resistance passive regen expires but other boni persists

[Farlius]

I also encountered this back on a 15 earthkin defender. Roughly 5 minutes as well.

[TooManyPotatoes]

I found this surprising because my character doesnt only lose mountain resistance regen but all other bonuses associated with stance. This is with regular stance, however.