Site Members Invitations & configs using signups only

[imath]

I've recently noticed the Site Members Invitations feature was only available on regular WordPress configs. If it's a multisite one or a a "single" site one using the BP_SIGNUPS_SKIP_USER_CREATION constant, it just fails activating the account.

I think we shouldn't rely on this bp_get_user_meta( $user_id, 'activation_key', true ); or the wp_user ID for the feature. BTW, imho, WordPress single site shouldn't create the user on "single" site registration.

I wonder if the invitation hash used could be replaced by the activation key so that we could directly query the signup to validate the invitation instead.

I'd like we investigate this improvement which would make the feature available for all BuddyPress configs.