That is why, while we used our BRD's track, we did not rely on it. We actually WENT there, doing the recce runs like in the olden times, eyeball (visual) style. Not just by one person, but by several - i think eventually the whole group had checked every room himself. Someone mentioned an overlap above, of despawning mobs and possible clue-droppers - perhaps that's the reason? Anyways, the "fix" could be as simple as removing the fluff drops (books) and replacing them with (additional) clues. Ok, perhaps not "simple" as it would also mean the creating of 3 more items, possibly 3 times however many classes can be selected depending on how the task is structured in the backend. OR a really crude but i guess quick fix could be to actually mark the books as valid proofs (substitutes). Because really, we can often tell from just two item drops (with sufficiently excluding class-combinations, like "WAR,CLR,PAL,SHD,BRD" on an armor piece and "CLR,DRU,SHM" on a 2nd drop) with 100% certainty which class the murderer is anyways. And since the books drop from the mobs in the task already, we would also have had to kill them, so do the task still "as intended" (just with less or no chance of it bugging out AND potentially making it quicker)?