When using the middle click sort function on a dank it will delete items in stacks of over 64 if there are multiple of the same item.

What you need to do is edit your config/inventorysorter/blacklist.json to look like this

{
	// Inventories that should not be sorted
	"blacklistedInventories": [
		"tfar.dankstorage.client.screens.DockScreen",
		"tfar.dankstorage.client.screens.PortableDankStorageScreen"
	]
}

Middle-click to sort will function normally after that.