would this make any difference to being able to edit?
Unlikely. How large are these images?
One is 2857 × 2250 and a few others are more! I usually make them a lot smaller but the other user has uploaded these. I can’t think what else it could be.
Are you trying to caption these larger images?
Yes. I just altered a caption on a smaller image and it changed so it does seem as though it has something to do with the size..
I have asked the other user to upload the images again smaller to see if this works.
It could be that the larger images are causing a memory issue. Whilst you could try increasing the memory available to PHP to compensate for this, reducing the size of those over-large images would be a far better idea. Your hosts (and your site’s performance) will thank you for it.
Thanks esmi! It seems as though this is the case. All images will be re-sized. How do I increase the memory available anyway?
There are a number of methods listed on http://wordpress.org/support/topic/253495#post-1017842 What works for you will very depend upon your hosts.
