File Block - Getting thumbnails to show correctly

Good Evening. My site, running Concrete 9.4.3 under PHP 8.3.23, has a page for files that visitors might like to download. For that I have used a file block and that seems to work fine except that where I have been expecting a thumbnail picture of the first page of the file I get a standard PDF icon. The thumbnails appear if I look at the folder from which the files are drawn in File Manager so they do exist. I presume that there is tick box somewhere that I have filed to find. I had thought that setting the icon size too small would be the problem but changing that does nothing.

My apologies for raising sucha trivial question, but it is something that annoys, mainly because I cannot find the right parameter to tick.

Have you seen this?

It may help.

You can add thumbnails to files. I had a load of pdf’s and the client wanted to show the front cover so we added images to the pdf in the file manager as a file attribute.

I then used the list from files set addon to show the files but added a custom template to output this attribute.

Many thanks for those suggestions. My problem is PDF so it looks as if I will have to make images and add them to the PDFs. I wonder if some clever person has written a tool for that? I will investigate.