I can no longer preview text files (e.g. `.txt`) in Finder. 

All I get is a preview pane showing a black square and TEXT.

[![server1.txt failing to show me the contents in preview](https://i.stack.imgur.com/qCZPj.png)](https://i.stack.imgur.com/qCZPj.png)

Other files such as `.tex` files show a normal preview of the contents just fine. I think this changed after I installed Sublime Text, although I could be wrong.

I've tried installing `qlstephen` but this hasn't helped my problem.

Any suggestions much appreciated!

OS X El Capitan (10.11.6) MacBook Pro Retina.