View window not displaying properly

My viewer window is showing images/videos chopped off in the left hand side of the viewer window. Worked at first, but now will only display chopped off images. Any ideas?

Is it just set to a different zoom mode? The buttons at the top of the oreview pane let you change the mode.

No, I tried that. Think it has something to do with file format. I found some videos display correctly but many display extreme left justified. Thereby cutting off the video unless shown full screen out of the viewer pane.

Is it the same in File Explorer for those files? If you're using the Windows Media Player preview handler, Microsoft broke that some time ago in a Windows 10 update. The ActiveX control still works but the preview handler does not.

(Edit: The preview handler works again in Windows 10 1803.)

I’ll look at that. Are you saying I can change the handler?

Yes, there are normally three options for movie playback in the viewer, although Microsoft have broken one so it's more like two at the moment.