Re: User’s blogs are going to a blank page
So, your main site is wp multisite and you’ve tried to activate bp on a secondary blog?
Amend: See the reply from @r-a-y to this thread: https://buddypress.org/community/groups/creating-extending/forum/topic/buddypress-not-on-themainblog/
Why haven’t you activated bp on the main site as that is your multisite primary blog?
Deactivate bp on your secondary site, install on your main site and let us know if your links then work