There is a pending bug fix coming up in the update. The bug appears when you toggle/change the visibility of sections which are not defined. For example, you toggle the visibility of Events, but you've not enabled Events in your site or you toggle the visibility of Drive but you've not installed buddydrive in your site.
Please set the visibility to "everyone" for modules you're not using. This fix would be available in tomorrow's update.
https://trello.com/c/8wn1q8ir
For the second part please share if you're using the modern child theme ?