Hi, I got the exact same problem as Gulfstream today. After a dist-upgrade of my debian testing system, fcitx does not start automatically any more. Output of fcitx-diagnosis is the same as gulfstream pasted.
I fixed this accidentally when trying around. I deleted ~/.config/fcitx. Then I rebooted several times but it does not help. Then I tried to login with a gnome-classic session. Fcitx started and it worked fine. Then I log out and re-login a gnome session (gnome shell). This time fcitx started and worked. I tried reboot the box and login to gnome shell, fcitx started and worked. Hope this helps! Best Regards, Hongjia Cao