Problems with bulk edit products

Hello,
I’m having a problem with the bulk edit feature. When I try to change the category of multiple products, it does not allow me to reassign the category of a product, rather I am only able to add an additional category to a product. The end result is that the product appears in both categories (the original category and the modified category).

For example, I have 3 products in the table (mesas) category (seen in img 1) and I would like to be able to remove them from their current category and add them to a different category such as chairs (sillas), as seen in img 2. What’s happening is that I am only allowed to add the products to the chairs category and cannot delete them from the table category (demonstrated in img 3).

img1:https://immograf.com/wp-content/uploads/2015/07/1.jpg

img2:https://immograf.com/wp-content/uploads/2015/07/2.jpg

img3:https://immograf.com/wp-content/uploads/2015/07/3.jpg

Any suggestions to resolve this issue would be greatly appreciated. Thank you.