Check the filenames, and the names of the folders that hold them, for "illegal" characters.
What do you mean illegal characters? The links are images.
things like / ? < > \ : * | "
only letters, numbers, dash and underscore are safe to use.
If these are anywhere in the file name or path, they can cause this issue.
Any character in a filename other than a-z, 0-9, hyphen or underscore could cause this as they are not allowed in Linux file naming conventions. (brackets or parentheses might be OK, but I'd avoid them).
Not every character is allowed in file names or folder (directory) names, other characters are causing names.
You should only use the normal alphabet A to Z and a to z, numbers 0 to 9, underscore _ and dash -.
Everything else has to be avoided. Slashes \ and / are forbidden, don't use & and % and don't use Umlaute (äöüÄÖÜ), don't use sharp s ß, these are causing often problems.
Use simple characters as above without space.