Batch update for events participants limited

[RachelWright]

I'm curious about batch updates for events, I have several custom sets of data set up for various event registrations. Some of them I have set up to be Used for "Participants (Event Name)" and I select each of the pertinent events for that set.

Custom Sets set up this way can not be edited via Batch Update. A custom set that is set up to be used for Participants (Event Type) or Participants (Role) can be edited. Any idea why?