Re: 1.2 can't function independently
The answer is not to use the bp-default theme anymore.
Switch to bp-classic or your own theme, and you’ll be back to normal.
The purpose of BP out of the box, is to provide you with everything you need to make a social network, including the theme to do it. If you haven’t been making your theme a child of bp-sn-parent, or you made your own custom theme, then you’re on your own as a developer to fill the gaps in your custom theme.