B4J
B4A
The video does not show the dragged file because the ScreenVideo does not record the Mouse.
But the file is dragged correctly, but is not released, in the file window (of B4A) it becomes a cut circle.
Note how the mouse cursor should look. I guess that something on your computer interferes with the drag and drop task. Anyway as there is a very simple workaround I'm leaving it open for now.
I found the problem. I set B4A.EXE to work with administrator privileges, this prevents (I don't know why) that the DRAG & DROP is done. Now after deactivating the administrator privileges everything works correctly.