I realised after posting that I'd confused myself - I assumed that both dreadnaught nightfalls would unlock separate calcified fragments (especially as XLV references a cell like the title of the darkblade strike). However when I did this nightfall on my main I forgot to see if I'd unlocked a new fragment, but when I did it on an alternate character I did unlock a fragment, forgetting that it was just unlocking XLVI for that character... Also I can see that the festival of the lost has now been added. Thanks for responding! P.S Do you know whether XLIII, XLIV and XLV are even available in game yet? :)