Hello. I wanted to insert a landscape page in a Portrait-oriented document, while keeping the other pages portrait. I googled it and managed to do so.

But now, each time i want to change the orientation in an already existing document or a new one, it only changes one page, leaving it blank, and the rest stay the same orientation. Can anyone help with this issue?
Here's a link with the printscreen: https://ibb.co/gNCT5v
Thank you.