Thanks Abz.
Having checked for conflicts and I have found that the plugin “All in one SEO” was causing the issue. Have resolved by deactivating this plugin.
Thanks so much! I’ve given this a try and it has worked on most pages :))
Thanks for this idea fix. Not working though, I’m afraid.
I’ve just found a similar issue reported in the forum before.
Could this be the same issue reoccurring do you think?
https://wordpress.org/support/topic/images-stacked-vertically-when-default-gallery-display-style-is-selected/
Thanks so much for your help :))