Maybe a bug which can be cause by adding new asset? + Widget Blueprint bug?

https://answers.unrealengine.com/questions/741125/widget-bp-or-c-player-controller-causes-packaging.html

When I add assets consecutively, the added assets sometimes fail to edit.
Also, there seems to be a bug related to the Widget Blueprint as shown in the link.

I have a project file that can not be compiled due to a widget blueprint bug, and a project file that I have resolved.