ArcGIS Online no longer allows me to create new Web AppBuilder applications from the Contents page as well as from any other web map. The application after creation is only displayed as follows:

And I also tried creating in many different web browsers but the situation is still the same.
In addition, for the previously created Web AppBuilder Web applications, I cannot reconfigure them, the interface when selecting the Configure App button loads as follows:

It loads forever and does not stop. Looking forward to the help of everyone. Thank you very much!
Thao Nguyen.