Comment 8 for bug 972785

I discovered that this might be the case if somehow your ~/.config/autostart changes it's owner to root. To check if that's the case, do:

ls -l ~/.config
if the output is something like this:
drwxr-xr-x 2 root root 4096 Out 19 17:22 autostart

Then all u need to do is:

cd ~/.config && sudo chown -R autostart "yourusername"

And you are good to go. At least fixed my problem.

Cheers