Console: PC, XBox, PS2, Any
Process: Fighting multiple monsters with a summoner.

Steps:
1. Send Avatar at any monsterer(henceforth MonsterA), and attack another target (henceforth, MonsterB).
2. Give Avatar command to use a Blood Pact Rage on MonsterA, and before it completes it, kill MonsterB.
3. Avatar will cancel it's use of Blood Pact and the ability timer remains used. It's target is still valid, but as you killed a mob, it cancels the blood pact as though the target died.

This has been an issue, according to a summoner friend, for a very long time.

I have also noticed that while wandering in the Temple of Uggalepih, when the avatar fails to complete a blood pact, until zoning or logging out, any macro that uses a targetting command such as <st> and the <wait 1> command will error repeatedly.

If for example, your macro is:
/pet "Healing Ruby" <st> <wait 1>
then you will receive an error message that there was an error processing '/pet "Healing Ruby"'. This error has not come up since I reverted the macro to use the separate /wait 1 lines, and am unsure what causes it.