Re: Page Not Found within BP from Members tab: File location problem?
The default BuddyPress theme, under bp-themes, is the correct place. Any other themes go into wp-content/themes/ as usual. There’s code-magic that makes the WordPress theme page look in the bp-theme folders for the default theme.
I believe your problem is your install path. To quote, “WP installed as a subdirectory (mainsite.com/members).” BuddyPress uses the url “/members/” for its members component. BuddyPress gets confused when you install it in a directory with the same name as one if its components (it can’t parse the URL).
To fix: either reinstall WordPress into the root of your site, or in another directory that’s not called “members”, or try putting this into your wp-config:
define ( ‘BP_MEMBERS_SLUG’, ‘users’ );