Last night my guild was running Vet. MoL. We encountered (for my first time, but apparently this is an old bug?) one or more 'troll' pillars on the first boss. I am including a link to the twitch recorded by our raid lead. I imagine she might have already contacted someone she knows about this issue, but I wanted to make sure.
Start around 14:56, I believe that is around the time the issue is discovered.
https://www.twitch.tv/nbshadowthief/v/96820998