Uploaded Images not displaying

Hello,

I have an issue on a multisite where new images that are uploaded are not showing on the front end of the site, but it only affects images that are Featured Images. I can add images into the content area and it displays fine.

It seems to be affecting both multisites, but some images display fine on one site but not the other.

Here are the sites:
https://new-sherrydesign.co.uk/blog/
https://sydney-sherrydesign.co.uk/blog/

You see on the first site the images are fine (although the are other images on that site that don’t display), but on the second site the same images do not display.
Not sure if it makes a difference but the ones that don’t work were all uploaded after multisite was installed, the images that do work were uploaded before multisite.

Heres my .htaccess in case that’s where the problem is:

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# uploaded files
RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]

The site image upload path is set to /wp-content/uploads/

Any ideas would be much appreciated, thank you.