.kra files from Krita.com are note supported. They are supported in Windows.
Please support the same file types in OneDrive that are supported in Windows. I currently use a graphics program called Krita, and .kra files,which are displayed properly as image thumbnails in Windows, are not displayed properly as images in OneDrive. Please add this functionality; there is also a lot of chatter on the net about other file types that are not supported.