Since a recent commit to master, directory size calculation (in number of entries) is not reliable. - the number of files shown is often less than actually inside the directory after moving or extracting files - sometimes tree expanders do not appear, because Dolphin believes there are no files in there - deleting files inside a directory does sometimes not decrease the counter
*** This bug has been marked as a duplicate of bug 473999 ***
Note that I do not sort by size, but by name, and these error are still visible.