If your website won't load after updating to BuddyPress 12.1.1 it is likely a conflict with bbPress or another BuddyPress compatible plugin. Install the BP Classic plugin to fix this issue.

Okay
  Print

Comment form is not reloading after submitting comment

This will happen if you've added a Comment element to an end point tab. To fix this you also need to add a Comment element to the main page (your hub page tab). You can hide this Comment element by editing the Comment element, click the Advanced tab, under the Responsive toggle enable Hide option for all sizes.