I'm using v1.8.6 of the app.
When I try to change my existing zone settings (specifically, I'm changing from a fixed spray head to an emitter), I get an "error" dialog box, with just an OK button to dismiss it. The content of the dialog box is actually the HTML source code for a webpage. The whole thing won't fit in a screenshot, but it seems to have the following, if it gives you any hints:
< title >Action not found< /title >
< p id="detail" >For request 'PUT /'< /p>
I took a couple of screenshots of the entire error dialog. Let me know if you want me to email them to support.