Here's what it looks like:
I've had this happen a few times over the years and I have no idea what I did to fix it. I spent about an hour trying to fix it yesterday looking up other forum posts but I couldn't fix it with the time I had. I set nd reset the default apps for CDR files and the "opens with" app settings. I uninstalled the windows shell and re installed it. I uninstalled and reinstalled Corel x8 as well with no changes to this issue. I did have Corel 2019 installed before and when I chose that as the default app it did show thumbnails. Thinking maybe they conflicted with each other I uninstalled 2019, that made no difference. We use X8 because there is a macro that doesn't work on the 2019 version that's integral to our workflow. In case its relevant, CPT files also appear with just an icon.
Also, some files have only the icon and others have the thumbnail preview.
This is the case for CDR and CPT files, but majority (like 99%) of files have no thumbnail preview. There doesn't seem to be any sort of obvious pattern why the files are or aren't a thumbnail preview.
How can I fix this? It was fine a week ago, not sure what happened.
You can't, this according to the first time it happened to me is a windows issue. I use Mystic Thumbs to get around this. This started happening to me when windows went to 7. I had CD5 and then it started.
Usually, this happens when the Windows Shell Extension of Corel is buggy.Try repairing your installation and be sure to add the WINDOWS SHELL EXTENSION option.If it's not available uninstall it directly from Windows Add/Remove Programs.Then try again.Absolute last thing is to uninstall CorelDRAW completely and all its associated programs...Windows Shell Extension, Ghost Script, and the program itself. 3 items to remove.Then reinstall. Select custom installation so you can see ans select all the options you need. You will notice the shell extension in the variant options.Good luck!