remove # ← formatting issues with hashtag can create problems
Add Apt, in front of apartment numbers.
Apt & Suite numbers like Apt 3 should be in address line 1, or placed before street information.
If there is a Company Name, move it to Company Name instead of Address line 1 or Address line 2
Is it missing an address line 2?
PO Boxes should be in Address line 1
Company line is never verified
Maybe there are special instructions like, "Deliveries in Rear" which the customer wants on the package but cannot be verified, you can move this info to Company Name section since it will not be checked as part of the address.
Check if there is a missing digit in the zip code
If the address appears with no issue, and the house or apt appears in google maps, it may be okay just not an address that is recognized by the postal service.
You can email your customer to confirm the address.