I'm getting resources not stacking properly. They're moving from inventory to an empty bank space instead of the resource stack that is already there (and not maxed stack count).

I am seeing this as well. Certain items always do this, while most do not. Some examples of items that are not stacking correctly include Temporal Crystal and Talador Orchid. It isn't many items, but when your bank is nearly full, it greatly reduces the usefulness of the mod.