I have this problem as well.
It seems that the settings for Home Template (unlinked) are being ignored and using the defaults instead. Has just happened in the latest update to 5.2.1.
Yes, I second that – should be addressed immediately.
Some support would be great. Especially given the number of people who say it’s broken.
Ok, it seems to be conflicting with Lightbox 2.
In the file bp-activity-subscription-functions.php, comment out the appropriate lines starting at line 485 (add_action …..
Hope that helps.
