Media Library displaying cropped images

Using WordPress 6 and latest versions of plugins.

Suddenly noticing several headless images in Media Library I realised they had been cropped.

If I click on them, the correct full image appears. If I add them to a Gallery, the headless version appears.

In Media Settings I have “crop thumbnbails to exact dimensions” unticked.

Does anyone have any idea what has caused this and how it can be fixed?

Thanks