I have 2 CPTs named Lưu trú (Resort) and Quảng cáo (Advertising). Resort type Resort is in one-to-many relationship with Advertising type.
In template of Advertising type, I’m using Single Field to show a field, for example: Địa chỉ (Adress) from the Resort related post. But it doesn’t show up on back-end as well as front-end.
It's not clear from your screenshots why this wouldn't work.
Would it be possible to get access to your site to take a look?
Let me mark your next reply as private so that we can get log-in credentials from you—you may want to create a temporary admin user for us to use that you can later delete. And be sure to have a current backup of your site.