Title and Insert shots

Having trouble inserting shots. The stills (jpeg) are not shown correctly and editable!
Picking the image (a title jpeg) i get hash/garble/unviewable stuff in the Player that cannot be used.
I edited 5 segments with success (Fade ins, Fade Outs, cross fades and inserting an image over the primary video). Now I cannot do any of that and the images I used in other videos won’t work either!

I cannot Drag and Drop and the inserted shot is so thin that I cannot ‘stretch’ it to the time line.

What are you trying to show in the picture you provided? You have no files in the playlist or on the timeline, and you exported a video with nothing in it. And something is being displayed in the preview.

What exactly are you trying to do with the stills (jpeg)?
What Shotcut version are you using? Version 18.06.02 is the latest.
You can download the current version here: https://shotcut.org/download/
If you need tutorial videos, the basic ones can be found here: https://shotcut.org/tutorials/

Maybe your .jpg files are not really JPEG?
Try reinstall. From where did you download Shotcut?