There is a bugged data pad that you can read multiple times (mine was located in the Cosmodrome section of the reclaim activity). When you do that, you remove another data pad for each time you do it. There is only a finite amount of information that these data pads can give you so by getting more information through the bugged data pad you are taking away others. The bug is likely due to a connection between the data pads and information. The data pads are linked to "unread information" for them to appear, while the quests are linked to the individual data pads in each instance. So if you read multiple instances of information in a single instance it registers the pool of unread info getting smaller but doesn't give you the completion achievement for the place where this info should have appeared. (I'm not a coder but this is my hypothesis, it does feel very spagetti code-ish) In other words if you only read the bugged data pad once, then all the other data pads would still exist. That's why others can still find them, because they didn't read the bugged pad as many times/ only once. We have (not on purpose) basically soft locked ourselves out of the data pad collecting. You won't find any more data pads from this point on unless a fix is implemented. Bungie is aware that this has been happening (and how this bug interacts with players ability to rank up).