I have a large architecture project that I've been working on since before 2.79. At some point post-upgrade (to 2.8), parent objects (created with ctrl + p) stopped influencing their children. I can parent one cube to another but when I move the parent cube, the child does not move at all. The "child of" constraint works fine.
This problem only shows up in this blend project. If I create a new blend file, parenting works as expected. I found the blend file I was working on before I upgraded to 2.8, and when I bring it into Blender 2.9, parenting works fine. And when I delete all objects in my project except for 2 cubes, and parent one to the other, the child still does not move, which means other objects aren't causing the problem. This seems to indicate that a setting was changed that broke parenting influence but I haven't been able to find what could be causing it. The problem occurs in both MacOS and Windows 10.
I'm attaching a duplicate blend file with all original project objects removed.