The address validation indicator is displayed when an address should be reviewed before shipping the order. It doesn't always mean that the address is invalid; the address could be valid but still should be reviewed, possibly edited and manually validated.
The indicator is displayed in three cases:
1, Address is invalid (not deliverable). In this case, manually verifying the address will return invalid.
2, Valid address with warning (some details aren't fully provided or entered in standardized format. E.g. excessive abbreviation or missing apartment number or missing apartment number prefix). In this case, manually validating the address will provide a valid address but it is uncertain exactly which door the package is to be delivered.
3, Address is valid but ambiguous because multiple addresses are found that share the same 5-digit ZIP. In this case, manually validating the address will provide a valid address, but it is uncertain to which address the package will be delivered.
The solution for bad address is to review the address and edit the address if necessary. Then, manually validate it. And, contact the customer if necessary.