This is happening to my project (UE4 v.4.20) as well. Say for instance I have a parent blueprint with a structure assigned to it + multiple child blueprints, the child blueprints are wiped clean of any structure attributes any time I add or remove an attribute to the structure. This means I basically have to save all child blueprint structure attributes somewhere on a textpad and manually enter them in.
This gets difficult when a child blueprint has multiple attributes; especially items with name, value, weight, icon, etc.
I don’t know if version 4.20.2 fixes this as I’m in China atm and my download speed is terrible.
Unrelated, but UE4 consistently crashes for me if I undo (ctrl+z) while working in blueprints.