Sessions always saved, whatever is checked in xfce4-session

How to reproduce:

1. open "Session and startup"
2. uncheck "Automatically save session on logout"
3. shutdown or restart your machine

Expected result:

1. a blank session is started

Actual result:

1. your last session is restored
2. /.session contains your past session

Note that the setting xfce4-session "SaveOnExit" is correctly set to "Boolean" and empty.

Check on Manjaro, Xfce 4.16.