I know, I am late to the party and this may have been discussed before, but then I am not an achievement collector, I only do the easy ones or the ones that grant a reward.

I went to see, which new achievements had been added for the event and noticed, I was missing the Organ Donor. So I opened it up and saw, Brainiac was missing. Checking further the individual list indeed claims, that I did not have my brain taken. I cannot recall the exact notification, but am pretty sure, I did go through the whole process a couple of times, since I played on the forum thread throughout the whole event. I remember, there used to be issues with the brain (lol) during the event, but was of the impression, that eventually had been resolved?

I am not sure if they can look back into that but I would make a ticket since it is more of an individual error and see if they can do something that way.

This issue still pertains after (re)importing. I doubt, that I am the only one, because, as mentioned, I remember a thread about the brains being skipped/remaining unnoticed by the system at the time.

Again, I would make a ticket to have a UA look into this. If they still have logs on this, they would be able to look into this for you. I am going to actually lock this since this is a ticket issue.