Hello, we have the same problem, the image files do not open in the preview window like PDFs, but download instead. This is inconvenient, because you have to go to the explorer and look for this file.
Example process:
https://owwa.crm-onebox.com/815717/In this process, there are two files, the PDF opens in the viewing window when you click on it, and the PNG when you click on the image is immediately downloaded and there is no way to view it without downloading.