There is a question about the same problem as mine, but the problem is still relevant.
I have several categories of news and each user backend is authorized for one or more of them. Currently, in the backend module "news administartion", users can view news from all categories.
If users modify an unauthorized news item, there is a message stating that it does not have the rights, but is there a solution for the user to see only the news of the authorized categories, as it was possible with tt_news.
My system: Typo3 7.6.18 - tx_news 6.0.0
Looks like you nned just chose fo user or usergroupo sys category on Tab " Mounts and Workspaces" - > "Category Mounts:" (without root category). Then your backend user will see in backend news list newses just from this category.