However, I did find that if your add a 'gap_limit': 10 at top level in the wallet file then it does behave correctly and respect new addresses. ie. red addresses become normal.
Doesn't work for me. Where exactly do you have to place it?
I placed it immediately before the seed version. eg.
'imported_keys': {}, 'seed_version': 6}
becomes,
'imported_keys': {}, 'gap_limit': 10, 'seed_version': 6}