Reproduction steps:
1. Create a new 3D project
2. Extract the attached “DragAndDropFileinside.zip” somewhere not in the project directory
3. Drag and drop the “dragAndDropThis.fbx” file to the Project View

Expected result: Dropped file is added to the Assets folder
Actual result: Error “ReleaseButton expects buttonId >= 0” or “Assertion failed“ is thrown and file is not added to the Assets folder

Reproduced with: 2021.3.40f1, 2022.3.36f1, 6000.0.9f1

Reproduced on: Ubuntu 24.04 (Wayland), Ubuntu 22.04 (Wayland)
Not reproduced on: Ubuntu 24.04 (X11), Ubuntu 22.04 (X11), Windows 10

Notes:

• Unity 2021.3 and 2022.3 throws:

Assertion failed
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&) (at /home/bokken/build/output/unity/unity/Modules/IMGUI/GUIUtility.cs:203)

• Unity 6 throws:

ReleaseButton expects buttonId >= 0
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&) (at /home/bokken/build/output/unity/unity/Modules/IMGUI/GUIUtility.cs:219)