When editing a customer and adding a second site address, the Address Line 1 field is missing. Screenshot 1.
If I save the record at this point and then go back to Edit the customer that additional site address is here and blank. Screenshot 2. So I go add the details and Save the customer.
Now, if I go to the customers record, in the site addresses section, the street line 1 is missing again. And if I go back to edit the record, all of the details I added are there except Address Line 1. I think Address Line 1 has some kind of bugginess going on.