if there was no-one at a particular address on Registration Night it won't appear in the register at all. It is also possible that the only inhabitants were under 24, and not recorded as deceased, in which case their records would be closed, including the address. I was looking at some of the addresses where I have lived, and this is the case with two of them. The records for the .houses on either side are visible
Pedantic, I know, but the address itself isn't closed, just the details of the people there.
If you find the preview of a neighbour, then amend the number at the end of the web address (i.e. change 20 to 19 or 21) to work your way along the street, you will see the record appear, but with just dashes rather than the details. Also the top will just say "Household" rather than (for instance) "Smith Household". You can then see how many people are in that household.
As for a missing address in searches, if you look at the JPG that Guy put on the main thread, you will see that the address is in the first column and is only shown on the record for the head of household. If that person is redacted, the redaction INCLUDES the address column, meaning that the address as well as all subsequent details are witheld. So even if other householders ARE visible, the address will not appear in address searches.