Was playing through a level and the grim was stuck in the wall. It was taggable but unable to be picked up. See Photo…
IIRC i think you can actually pick that one up with a bit of finagling but it doesn’t fix the fact that its pretty hard to get to because of that and should probably be like visible apart from its glow
Yeah that one is pickable… I picked like 3 from that place just aim more at the floor 
But this one is not : It was map with the hive cluster of servoitors event on it a bit later & before one of the elevators.
imagine book spawning there… no glow… no book… that’s how we miss lot of stuff & time looking for those^
A few of us tried for a bit with no luck… disappointed for sure!