OS: Linux 64bit
Libformat version: 7.81
Effect: Confusing behaviour makes it look like the file is missing. XNView opens fullscreen showing only a blank background. When this happened to me with a video (because I had set the filter to images), I thought XnView was broken at first.
To reproduce:
1. Open XNView and set the Filter by setting to be "Video".
2. Go into Settings and check that under General, the setting for Mode when starting with a file is set to "Fullscreen - Browser".
[Note: It is totally not obvious to me what the difference should be between Fullscreen - Browser and Fullscreen - Viewer is.]
3. Close XnView.
4. Open a file manager and do whatever actions are necessary to make an *image* file open in XNView.
Actual behaviour (bug): XNView opens fullscreen showing only a blank background. Arrow keys and buttons at the bottom don't do anything and neither does Enter (even though this is a setting which usually switches to browser mode).

Expected behaviour: Selected image file is displayed. Pressing Enter should take you back to Browser mode if that setting is enabled. I'm not sure what the distinction is with the "Fullscreen - Viewer" mode, but if you have that setting, it shows the image and then drops you back into an empty folder if your selected filter hides all images.