If you are at 10 stacks of resolve and swap in an item having the Aspect of Tenacity to gain the 5 extra stacks. The stacks will remain at the count of 15 if you swap out the item again. (Aspect of Tenacity)
I do not know if it interacts with the Aspect of Interdiction or the glyph Colossal. It might be the tooltip which is not showing the right stack count.