Thank you for your message and we are sincerely sorry for this issue.
We arware of this issue. It seems the amazon kindle has changed something in the new published kindle books. It requires the latest kindle app to download it. For the books published before 2023, it still can be downloaded with old kindle app and can be decrypted with Epubor Ultimate.
Now we are working on this issue. Once there is a solution, we will let you know. The older kindle books still can be cracked with Epubor Software.
For the ebooks published in 2023, here is still another way to remove drm from this kind of kindle books if you have any kindle eink device registered with your amazon account. Please download the kindle books via "Download and transfer via usb" and then remove kindle drm with Epubor Ultimate. Here is the detailed guide: https://www.epubor.com/how-to-remove-drm-from-kindle-kfx-ebooks.html#meth4
Some of the latest Kindle books will not even load with Kindle Version 1.24. They throw an error and say to download the latest version.
Any workarounds?