so, I managed to get the invitation from Palin on the night before 2.4 went live, but didn't have time to start collecting Unknown Fragments. The following night I went out looking for places to collect the fragments and no matter what I tried I was only getting Sensor Fragments... turns out they're the same thing, but Palin's requirement text hasn't changed... had 45 of the things before I decided to give it a go at Palin's base and see if possibly the description wasn't updated... Is this a bug because calling a Sensor Fragment an Unknown Fragment on the unlock requirements led to a bit of confusion on my part?