Hi, I just installed ImageGlass and I set it as my default image viewer. I was ready to switch permanently and stop using the "Photos" app. However I have the same problem described above. In file explorer, thumbnails are not shown anymore and are replaced by the "ig" icon (it only happens when viewing as "list", but when viewing as "large icons" all thumbs can be seen normally). With this "list view" problem, it's almost impossible to switch to ImageGlass for everyday work. Here's a screenshot that shows the problem. Notice how ImageGlass is the default viewer for BMP, GIF, JPEG and PNG files. And also notice that I set JPG files to be opened with "Photos app", and those files show a thumbnail without problem:

Please, we want to switch to IG. Your help will be appreciated.
Thanks.