I'm having trouble getting critters into my profile foe.

1) I participated in a group pirate hunt and we took down critters (capped pirate captains) something like 70 levels over me and 40 over my profile foe, but they didn't replace it. I hit them with dispels which is rather more than I've done previously to get FOEs in this sort of group hunt scenario (swung and missed with a melee weapon).
2) I decided to get something appropriate into my profile victory, cleared the foe, and went looking for the right critter. Let a swarm gather, cast 335, danced round the corpses, but FOE stayed empty. Killed some more with directly targeted spells. Messaging says I need to kill something to get a FOE, I kill lots of things, but it stays empty.

I don't see anything on the wiki or in game messaging that says the criteria for getting a FOE are any different to what they used to be, but something seems to have changed or some bug has crept in.