Download folder in Dock not updating correctly

I'm having this slight annoyance since Yosemite, I can't seem to find a reason why this happens...

I added a "Downloads folder" shortcut in the dock, but the contents displayed in the shortcut list/grid/fan rapidly becomes erratic - it doesn't correspond to what's actually in the folder.

After a little while, the list of files when clicking once on the shortcut :

- mentions files that have been deleted since

- mentions multiple copies of the same file (despite the fact that the file has no duplicates in the Downloads folder)

- fails to update at all after a while

This minor problem is solved by killing/relaunching the dock : the list/grid/fan of files displayed by clicking once on the folder shortcut in the dock once again corresponds to what's really there... For a while.

I did :

- Reinstall Yosemite to see if the problem would be fixed, to no avail

- Check and repair the permissions

Anyway, I have no clue what I can do to solve this. Suggestions, anyone ? 🙂

Cheers !