The cause can be that Google Maps is unable to find the address.
To resolve this, you'll need to follow these steps.
Click Service User, then click Service User.
Click Find, then select the relevant service user.
Click the General tab, find the Postcode field.
Click the globe icon next to the postcode field. The address shows with the message Partial Match and anything it failed to match with a strike through and a suggested address below it.
Amend the address to the suggested address or something similar, then click the globe icon. The message Partial Match should no longer appear, meaning Google Maps can now find the address.
If you believe the postcode is correct, you can send feedback to Google using the Send Feedback option when the address is showing incorrectly. this can be reported here. As a short term fix, you are able to enter a * at the beginning of the line which is not being detected. this will cause the system to locate the address only using the postcode.