Interface:MC6840 is incorrect (it's a carbon copy of 6821)
When this symbol was last reworked, somehow it got replaced by a copy of 6821. I dug out a copy of the "real" 6840 from the old v4 lib at https://github.com/KiCad/kicad-library/blob/master/library/motorola.lib to show what it should look like (below, center)
Fix required:
- delete current MC6840
- recreate MC6840 or restore from v4 lib