i have a similar issue, it happens with anything i want to fast transfer, note i am using the keybind name not the default control scheme, as i remapped so many controls, i dont recall the default keys.
in order to get the items distributed evenly, i have to use fast transfer while hovering over the entity,
and have more than one stack of the item in my pocket, if less than one stack, all the items transfer and i can no longer distribute the items evenly,
after transferring into one entity, i have to hover over that same entity again to get the highlight, then over all the remainder entities,
after all that, then everything gets balanced evenly.
if i press the button before i hover over the entity nothing happens when i hover over the entity,