Dear Krileon,
Thank you, I solved the problem.
Long ago, we made a special template for the CB activity feed, to show the date in another format. (Exact date and time, instead of the standard 'days / minutes' ago)
This template caused the problem.
I guess I have to make a new template to change the date format.
Or did you build a new option in CB to change the display format of an activity date?
Regards,
Patrick