I unselected GlobalEventHandler for UE4. But problem does not changed.
And, I found one more strange thing: some widet blueprint, that is not created new - that means old one - is applied with electronic nodes. some User Widget asset is ok, and some is not. I have 28 User Widget assets, And 11 User Widget assets have problem.
If you need my project as sample, I can send it. Please tell me if you want.
I’m considering to test migrating assets to new empty project.
Edit: Migrating does not repair problem. In my test, if I copy everything from old User Widget asset and paste into new User Widget asset, then nodes are displayed as electronic nodes normally. So I decided to copy and paste everything from old User Widget to new created User Widget.