Kenya tree question

[CRAP! Another Hobby]

Starting yesterday, my Kenya Tree suddenly has stopped expanding during "lights on" time. The day before, we had a minor landslide in the tank which shook the rubble that the kenya is on...causing it to fall to the bottom of the tank.
Today, with lights having been on for 5 hours now, the tree is still in it's nocturnal constriction.

Any ideas what (if anything) is wrong? All my params are spot on!