Stat boosts lost when bleeding. Bug or a feature?

[sotbiii]

When you go down, sometimes you loose all your spell effects including bonuses from Vocarious feat, but sometimes you don't.
Are you meant to lose them or not?
Which ever way it is meant to be, it does not seem to work perfectly every time.

[EO]

It only happens if you would have been at below -10 HP and were brought back via the system to somewhere between -1 and -9. Buffs are automatically removed when you drop to -10 and below so there's nothing we can do about that.