Oh, I found another bug.
Failed to find script package for import object 'Package /Script/CommonUI'
Even though CommonUI plugin is clearly installed. That causes input action data to lose it’s rows and as a result, action widgets have nothing to bind to.
It seems that those plugin issues have happened before to other users and in typical Unreal fashion, the only replies are a bump and suggesting to hack into the plugin.
I would really appreciate any help with this or to just get confirmed whether it’s a bug or wrong setup on my end.
Changed the question to better describe this new issue.