I've been solely using Ubuntu GNOME on my Thinkpad X250 since version 15.10. TrackPoint and Backlit Keyboard ever since functioned completely fine. (I've been upgrading my Ubuntu every six months.) Until 17.04 arrived. TrackPoint and Backlit Keyboard simply stopped working. Fn+Space doesn't work anymore...
Any help to troubleshoot this?
[Facepalm] :-)
After some testing, I had to go down to the conclusion that it was a hardware issue. So I opened it up and one flat cable got unfastened. (See image) I just plugged it back up and it's done. :-)