Drag and drop prefabs into inspector

!(https://user-images.githubusercontent.com/67449199/94720552-3ea58500-031a-11eb-96a7-8ae1ed61f59f.png)

!(https://user-images.githubusercontent.com/67449199/94720367-01d98e00-031a-11eb-9321-8dbe80b44795.png)

I want to be able to drag prefabs to the inspector on the right.

I want to assign Fab 1 to a prefab.

The drag and drop functionality is not working.

I am using v2020.1.6.Personal of Unity.

I am using Ubuntu 18.04.

Please help.

!(https://user-images.githubusercontent.com/67449199/94807752-b379cd00-03b5-11eb-8121-9e980d40b372.png)
!(https://user-images.githubusercontent.com/67449199/94807791-c096bc00-03b5-11eb-9cf2-3ea6d57caf6e.png)

I solved this problem.

I deleted the prefab bullet.

Then I created the prefab bullet again.

Then the drag and drop started working.