White shows as black
All white (pure white such as paper, 0000, ffffff, etc.), shapes and even within linked images are showing black. Some pages are affected and some are not. If I go into the swatch slider CMYK mode, sliding K from 100 to 13 is normal, however, 12-0 starts scaling back down to black. I've tried linking to all types of images (TIFF, PNG, JPEG, transparencies). The file was fine last time I worked in it, but upon reopening this is happening. Is this a bug or a corrupt file?
Your screenshot shows that you have selected an image (linked/embedded) and applied the White swatch to it.
Could you share the file with us (email@example.com) to take a look?
Adobe InDesign team
Emily Sandstrom commented
This was happening in CC 2017, was briefly fixed when I updated to 2019. But is now doing it again. Feels corrupt.