It’s really weird, did the second guy ended in C (or even D) grade too? You still should get something, but trying to find some similarity. I’ll move your topic to #bugs-issues as it doesn’t seem to work correctly.
@Guvnor did some Titan loot analysis and have quite some data, so he might know if anyone was reporting the same or he would know about it (Titan Loot Project - A Data Farming Project! Answering "What can/could I get from the Titan?")