Synchronicity issue with `set dircounts false; calcdirsize`

I have this line in my config

map C :set dircounts false; calcdirsize

that is supposed to show the disk usage of every selected directory.

What I expect is the right side of the directory entries turning to "-" except for the the selected ones, which display their disk respective usage. Instead, I see the disk usage blinking up for an instant before turning into "-" too.

This is the same behavior as if I ran both command in inverted order manually. I only see the disk usage after triggering the keybind twice.

If I ran 1. :set dircounts false and 2. calcdirsize in that order manually, I would get the expected result.