Cannot add all to cart

Hi,

I’m encountering the exact same issue as specified here: https://www.ads-software.com/support/topic/error-wishlist/

I’m on an URL like ‘/wishlist/0D3508/’ and I’ve got 3 products in my wishlist and when I press ‘add all to cart’, I get the error saying ‘%s could not be added to cart because some requirements are not met.’.

I’ve disabled all plugins (except TI Wishlist and Woocommerce) and switched theme to Twenty Nineteen (updated fully).

I tested the above with WordPress version 5.2.3.

Next I updated WordPress to version 5.3 AND used the newly Twenty Twenty theme. This results in the exact same error.

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Another issue is that when I have the quantity field of a certain product filled with a number higher than 1 (in the wishlist), it still only adds 1 of that product to the cart. My expected outcome is that it adds the quantity given in the wishlist to the cart. Otherwise, why would this field be even there?
This happens when I press the ‘add to cart’ button of 1 product in the wishlist.

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Please advise. Thanks!

Erik