Images disappear when I add a link

Greetings,

I'm having a an issue, I add images to my site, as per normal, but if I add a link to the images once loaded, they disappear - take the link OFF, they come back.

Any thoughts/suggestions, please? Is this a CSS issue? If so, any code suggestions? I ask, as I looked online and some have suggested this could be a CSS issue with the theme.

Thanks for any help offered.

Regards,
Robert