“Gutenberg style box” does not seem to work

“category replace” does not work when the “Gutenberg style box” is selected in the settings. When the “Classic style box” is selected the “category replace” works fine.
Also if the “Gutenberg style box” is selected: when I make a new post and I select select “category replace” and choose the replace-category, this category is not being saved when I publish the post. When I select the replace-category again and update the post, only than the replace-category is saved.
Rather long message, sorry, I hope I made myself clear …