How to prevent this from happening in a fast way:
- Launch live edit
- Open quick build menu
- Enable 'Building to Prop" this removes structural integrity
- Place all the assets you want in live edit (place prefabs if you want many props)
- Switch back to UEFN and grab whatever you like from those assets. They ll never break again.
Epic really needs a general toggle structural integrity option, most of the creators dont make maps for FN building anymore.