I noticed that some thumbnails were truncated in a big grid slide in Newspaper WordPress theme.
I checked the size of the truncated thumbnail and found its height is smaller than that of the grid box.
The thumbnail size of 534x462px is required for the Big grids 1, 3, 4, 6, 10, 12, full 4 and 5. If the size of the featured image for a post is smaller than this size, the thumbnail may not be properly displayed.
If the height of the thumbnail image in a big grid slide in Newspaper is truncated, please specify the featured image larger than 462px in height.
If too many thumbnails are created when using Newspaper, please disable unnecessary thumbnail size under Newspaper > Theme Panel > Block Settings > Thumbs and Modules/Blocks. After specifying the size of thumbnails, run a plugin such as Regenerate Thumbnails to regenerate thumbnails, which will reduce disk size significantly. (One of things you should do is to regenerate thumbnails after you change the WordPress theme.)