The platform (web or app) uses maps from 3rd party to geolocate the addresses.
Please do make sure you're following the next advices:
Input the address and select from the drop down menu the correct postal code. Use the notes section to give further details like door number, block, etc.
Provide a valid phone number with its country code. Make sure the country flag is matching the country code.
If after these steps the issue doesn't get resolved please do Get in touch with Support.