So, I managed to find another CBZ that my sage refuses to acknowledge exists.
You can find a link to the file here:
https://files.catbox.moe/efpnw8.cbz
I simply copy the file to the storage, let the file transfer, and eject the ereader. Then, my Sage "imports" the file, reaching 6%, but then flashing to the homescreen. The file is not findable on the device. I only know it's there because I see it in the file manager when I plug the Sage into my computer.
Let me know if I should make a new thread for this, since it is a separate issue, even if I already mentioned it.