[Plugin: Watu] problem with the visual editor

I have very few plugins running on the site. I have to disable all of them to get the visual editor to work on WATU. Otherwise, I cannot write any questions in HTML or Visual. It doesn’t let me input anything. I’m willing to do this in order to develop the exam but it definitely is a bug.

https://www.ads-software.com/extend/plugins/watu/