Can't see some photos

[london60]

I am having a problem where I can't see the photos uploaded by some people in the forum threads. This only happens with a few individuals, but it's every time they post a photo.
These are people I follow and/or am followed by, and we still exchange messages in forums and private conversation, so I know the problem isn't one of being blocked/ignored.

Any ideas why this happens and how to rectify this?

Many thanks.