Hi,
For some reason (which I cannot figure out), the video portion of the video and audio in the Timeline has disappeared - i.e., I cannot see video in the Timeline, although the audio waveform can be seen in the Timeline.
As you can see from the accompanying screenshot, the video is present (and plays properly) in the preview window, so I am guessing that I have done something that has corrupted or toggled-off the ‘display’ of the video in the Timeline.
Check that Timeline > menu > Options > Show Video Thumbnails is still on/checked.
If it is restart Shotcut and see if they work.
Also, from your screenshot it looks like you are using a proxy as the source video. Look at the file name.