Had this issue with previous versions of BP Activity+ and this continues to be an issue. After initial install all okay, then without warning the plugin breaks and no longer displays on the buddypress activity stream page.
BUT it is still visible on the buddypress member profile activity section.
I am running; WP 3.9.3 and BP 2.3.3
I have also attached 2 images, one showing the activity stream without the plugin functioning and one showing the member profile activity page with the plugin active.
Hope you can advise how to fix this.