I don’t know all the situation which lead to this, but I do see that boolean difference - which in my case at the moment creates many objects from a single object - resets the section properties of the resulting objects. I think it would be preferable for an edited object to retain those properties.
Yes, this is a known issue. Some Rhino commands, like boolean difference, create new objects instead of modify the existing one. New objects are added to the document will lose all parameters or sections properties. We’re trying to find a way to solve this issue.
This issue also happens when an extrusion is converted to a polysurface, which boolean commands always do with input extrusions.