Can different calendar apps coexist without interfering with each other?
This may not be the solution to your problem, but this is what I do to choose which calendar(s) to display on the app.

I see that you use Business Calendar app, which I am also using.  Under "Calendars &amp; Task lists" setting you are able to "favorite" your calendar(s) to be displayed at the bottom by tapping on the star(s) on the right.  Once done, I just have to tap on the bottom buttons (those favorite) to switch between my personal and business calendars.

Hope this helps.