I assume this is the bug that we have as well. We have several 25 man's scheduled and I added a bit more text description to several of them. Now when we look at the event details you can still signup/modify signup and see the signup summary (just numbers of Awaiting Approval, Waiting List, Approved, Denied, etc) and you can click and view the Event Log.
What is missing is the listing of signed up folks by role/class. javascript:rebuildevent(LanPartyid) builds this I believe. Ironically those who have said they would not attend do show up.
I see that DKPSYSTEM logged into our site (blades.dkpsystem.com) and remedied the current symptom for our 25 man raids. For that I salute you. May I ask that you return and do your magic on the other raids (10 man) that are still afflicted?
Also, I'm curious for an update- is the causing issue located and remedied but all existing situations need to be manually remedied or is it simply that it is known how to remedy the events individually but the root cause has yet to be discovered and/or fix deployed?
The solution is actually simpler than you'd expect, and the problem shouldn't arise again once you've taken care of the existing events. If you head to Admin > Event Schedule, edit the offending events, and at the bottom, just check the boxes next to the roles. Then save. Your roles should re-appear.
As far as I know, all the issues with this have been resolved (with the exception of the changing absentee bug, which I'm working on right now).