Image uploads but doesn't display.

Hi all,

Just set up a new wordpress site on my domain. I upload a photo through the “New Post > Add media” button. If it’s a small image, it works fine. If it’s large (as in more than a MB or so), then it takes a while and returns an error message – An error occurred in the upload. Please try again later.

The image does not generate a thumbnail. When I come back to media manager later, the image is there (still no thumbnail), and if I copy the link into a new tab I see that the image has in fact uploaded onto my host fine. The image is located at /wp-content/uploads/2015/11/afvb1.png

I’ve tried changing the name to remove any hyphens or anything like that. The file has the same permissions “-rw-r–r–” as others that work fine on the website.

Thanks,
James