Non stackable, stackable issue.
 

titanium client and 7.0.816 build

If you pick up items that are numbered like they stack ... but they don't stack ..... don't force them to or they will be destroyed when sold , zoning , logging in and out etc. Example, Blocks of Acrylia ore in shadeweaver thicket. (all sizes) also some types of sonic wolf paws.

Trying to unstack items that you shouldn't have stacked to begin with ... deletes the ones you unstacked and may delete all items of that type from your inventory, very annoying.