I have moved to a new theme then used Force Regenerate Thumbnails to regenerate post images, but after 24 hours of FRT working, I found a lot of images are missing from my posts. Maybe because my website relies on different sizes of the image.
Using chrome debug, I can see such an error (Failed to load resource: the server responded with a status of 404 (Not Found)
So, I tried to add the_post_thumbnail( 'medium' );
function to my theme but it didn't work.
Is there any other function that could REforce WordPress to regenerate thumbnails or call the medium image size to replace the inserted ones?