big lichen in arena doesnt drop anything (is this a bug?)

I know some people said the middle stage lichen (spikes, but not the dark red one) had a bug where they dont drop loot. i havent found this true in most levels, but in the arena when they appear in the final set of enemies for the first stage of the arena, they dont drop anything. that sucks!
is this normal behavior? i think i have had the trojan knight not drop things before either, so maybe its normal. didnt want to report to bugs if it wasnt one.

it spawns that way, its not the result of merging lichens :(
guess its not supposed to drop loot then
Ive encountered a few that instead of a Knight, a Lichen spawns as the end monster for the first room, and he never drops loot, and with no lichens nearby, is just a empty monster that must be killed to get the good stuff later. Hope they do adress this soon, just a bit irritating to know that Ill be getting nothing for taking it on.
This have never happend for me..
Every single Lichen I killed, any size, have dropped loot.. And bigger Lichen have dropped more loot then the smaller ones..
Happens to me all the time in the Robo Rampage Arena.
No idea what's that about.
This happened to me once too, I /bugged it. Sure they'll fix it at some point.
If there's only a single core in a colony, it's not ready to be killed. It needs to be a cluster.