No, it is bugged. Sometime the items get split for some reason and they do not automatically regroup together. The solution is to give all of them to the retainer and then take them back.
Regarding the inventory sorting once it will be available it will be always too late. I still can't believe I couldn't find it. Any news about when patch 2.1 is coming out?
BTW what's the use for the wet bombard ashes apart from buying the bikini (well, and the absolutely fun fireworks. I feel so stupid running around after lighting them! ^_^)?