Error: Missing image files

[nessn2]

Yesterday I started transitioning to the new .mokuro format and processed a couple of shorter manga, adding them to reader.mokuro.app without issues. Then I processed a longer manga (Houseki no Kuni), but when I try to upload it, it says "Missing image files".

So I tried manually adding just one of the .mokuro files, same thing. I tried with different volumes but the same problem persists.

I flushed the persistent storage manually from Firefox, which deleted the manga I had added, but it still doesn't allow me to add Houseki no Kuni.

I re-run mokuro --parent_dir ~/manga-dir and it scanned the whole thing smoothly within seconds, showing that nothing is missing. I also checked the image files visually and nothing is missing. I know the OCR is within the .mokuro file, but I also checked the OCR directory as the command was generating the files for the older method, and if a directory contains 160 images, the OCR directory also contains 160 images. I would assume the .mokuro file also contains all the images.

I tried with Brave browser: same thing.

How can I fix this?