Steps to Reproduce

1. Login to a character
2. Place items randomly throughout multiple bags
3. Click the button to Clean Up Bags

Observed results

The items from the bags are sorted into their own individual bags and not within the window itself. Within their own bags, they now show at the upper slots of the bag within the window and not the lower slots of the bag (As seen in image)

Expected Results

The items should be stacked into the lower part of the bags as they were in V3

V3 bags had a custom sort implementation, but due to a poor implementation and other fundamental design choices, it works well when you sort bags, but when Bank or Reagent also have to be sorted, it can cause your client to lock up for undetermined amount of times.

V4 is currently using the CleanUp function provided by Blizzard, which leads to this weird sorting behavior because it's probably taking default UI bags layout into account. Compared to porting the old sort algorithm, using Clean Up does have the advantage of being near-instant.