This was a nuisance on PC. However, at least we could easily click and drag duplicated stacks onto one another to neatly organize our inventory. On console, this problem is absolutely horrifying, even after buying thousands of gold worth of inventory slots. The only way to possibly wish to solve a stack issue currently is throwing everything into the bank, and taking it back out, hoping it'll get it right this time around.
This stacking issue is even more of a problem since the TU update; legerdemain. With the introduction of thievery, you can now waste even more bag slots with all of your stolen stacks as well!
Hopefully, this will be looked at and we will be given an option to combine stacks without stopping our adventures, quests, dungeons, or delves, just to go to the bank to fix stacking issues.