This error has been present for some time. I kept hoping that the Amazon Kindle Team would find it and fix it, but unfortunately this hasn’t happened.
So here it is:
After a Kindle book is archived in the ‘Manage Your Content and Devices’ section [https://smile.amazon.com/mn/dcw/myx.html], it’s impossible to download via the 'Download and transfer via USB’ option.

Of course, eBooks can been delivered wirelessly to a device, but if one ever has the need to download a title manually….
Selecting 'Download and transfer via USB’ from the Actions Menu of ANY library title returns a popup that states “You have selected content that is not compatible with any of your registered devices. Please remove incompatible content from selection for eligible devices to appear.” All the devices in the dropdown menu are ‘grayed out’.

Considering I have not one, but two Amazon Kindle Fire Tablets currently registered to my account, it seems that the content management system does not understand what constitutes an eligible device.

(The error is not browser specific, as I have tried to download titles using several different browsers — Chrome, Firefox and Safari — but received the same 'no eligible device’ popup.)
NOTE: If 'Transfer via USB’ is selected at the time of purchase, one does not encounter this error. It occurs once the title is archived “in the cloud”.
This is my 'Fix It Ticket’.
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