This is really hurting my productivity. Just upgraded Unity to 2018.1.0f2 on Windows. I installed ProBuilder via the Package Manager. Current ProBuilder version is 3.0.6. Follow the steps bellow to recreate the bug.
Create a new project and install ProBuilder via Package Manager.
In an empty scene, create a cube, turn it into a prefab and delete the cube from the scene.
Create a new ProBuilder cube with Ctl + K
Drag and drop your cube prefab from the Project view onto the the ProBuilder cube in the scene view.
Expected behavior A copy of the prefab should be place in the scene where I drop it Actual behavior I see a preview of my prefab and as soon as I release the mouse button to drop the prefab, the preview disappears and no object is dropped into the scene.
Tried to track this one down. Unfortunately there is no source but the problem might be in pb_DragAndDropListener.cs. I can only speculate. Maybe the Use() method is being called on the DragPreformed event when it shouldn’t be?
It doesn’t happen when dragged into a non ProBuilder asset. It is still not as convenient but in case it helps some one, as a workaround in the meantime.