Why do pictures not show on linked contacts?

[AC Question]

I have a new HTC 10. I've added in my my various accounts like Exchange, LinkedIn and Whatsapp etc. However, for the majority of my contacts, which have been linked, there is no picture shown on the contact, even though a picture exists in the Whatapp contact.

Exchange photos and Twitter account photos seem to show, but Whatsapp doesn't display. When I go into Whatsapp by clicking the icon in the contact detail, the individuals image is available.

Any ideas?

Regards
Lee