How to reproduce : 

1 - In a project, add a file, in my case it is an image. 

2 - Once added, click on the "eye" to open information about this file. 

3 - File is opened in a pop-up : 

4 - Select Delete button and confirm. 

=> File has been deleted and pop-up is closed. 

File is not present in the left panel, but information about deleted file remains in the right panel.