Waterstones usually sources books from Penguin Random House through credit and then raises funds to pay the publisher back by selling its books, but credit lines are understood to have been weakened since the end of 2020.
The dispute could have a knock-on effect for the availability of the most sought after books – including The Bench by the Duchess.
Last month, Meghan confirmed she had put pen to paper on her first book and The Bench tells the story of a special bond between father and son – inspired by her son Archie’s relationship with Prince Harry.
The book was based on a poem the Duchess wrote for her husband a month after Archie was born in 2019.
It has been illustrated by Californian artist Christian Robinson.
Meghan said: “My hope is that The Bench resonates with every family, no matter the makeup, as much as it does with mine.”
The Bench by the Duchess of Sussex is due for release on June 8.
Follow Express.co.uk for live Royal Family updates: