The problem is that I can't type anythin into text box. Also Backspace and delete buttons don't work.
I can confirm this bug (it bogs me too). loki 0.4 is running on an Intel-based PC using Kernel 4.4.0-36-generic
When I investigated into it I found that different users have different behaviour (typing is possible for another user). I created a new user by
sudo useradd -c 'elementary test user 0' -d /home/elementary0 -m -s /bin/bash elementary0
added a password.
When switching to that user the input/search works.
So it might be that some "old user settings" causing this behaviour.
Could someone help, which settings causing this behaviour?