It doesn't seem to matter how many times I run the Sieve with my Titan, the Melas Panoplia exotic armour just won't drop. After completing the Edge of Fate campaign with my Warlock, Eunoia dropped on my second run through the Sieve, and every run since. Similarly, Moirai has dropped every time my Hunter has completed the Sieve. Neither my Hunter nor my Titan have done the Edge of Fate campaign, but I purchased completions for both of them once the option was presented to me. This is the only thing I can think of which might be relevant, but if it worked for my Hunter, surely it should've worked for my Titan. A fix for this apparent glitch would be great!