Menagerie - Farrul's Den Activation Failed.

Two times today, I have experienced that the Portals to Farrul's Den is not opening/appearing after activating it and killing the mobs at the Blood Altar.

All it says are " Activation Failed. Unable to open portals to area".
The (expensive) beast(s) used for activating it, has been removed from my Menagerie and are apperently just gone for good.

Should say that I have managed to do 4 x Farrul's Den without any problems.

Would be nice with a few / info / solution to this, since it's an expensive loss. Tried relogging / Changing char / Changing server - and reentering my menagerie, but without any luck.