In Roundcube Webmail, when accessing emails with an image attached, the email text is fine but the images cannot be opened. There is no thumbnail nor the image itself.
When the same email is opened in a different email client (eg Thunderbird), the attached images open, no problem.
Using:
Roundcube Webmail 1.4.1
Installed plugins
Plugin Version Licence Source
filesystem_attachments 1.0 GPLv3+
jqueryui 1.12.0 GPLv3+