Seems like gutenberg was the problem. After disabling it they came visible..

If I am in the portfolio arcive by tag, it would be nice to be able to sort all portfolio items by category in that archive page

Hello!

Thanks for the reply! I just took a look of the link you provided and found out that there was a use_main_query_pagination -> yes used in the attributes and it seemed to solve the problem to take that one line out :)

Sure!