[crane3]

From maplepop (maple reader) FAQ:

How to import all books from Calibre in one shot?

By default, Calibre's Content Server returns a maximum of 30 OPDS items per query. If you have hundreds or even thousands of books there and want Calibre to return the full book list with just one instead of tens or even hundreds of queries, you need to change that maximum number.

From the top menu, open Preferences > Preferences
In the Preferenes dialog, open Sharing over the net
In the Sharing over the net dialog, change the value of Max. OPDS items per query from 30 to a number larger than the number of books stored there, and click Apply
Click the Stop Server button if applicable
Follow the instructions of “How to import books from Calibre?” as needed
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The selection is way down after the max cover size.

edit: forgot to say that it would be a good idea to reset the max feed item back to 30 or so for when just getting updates. Calibre may send the same send the same high items when you just need to add a couple of books...