2016 South African census - Missing municipality codes

I have downloaded a multi-country extract of contemporary census microdata for people aged 27-33 (inclusive). In the case of the 2016 South African census, I find that GEO3_ZA2016 (the municipality code) is missing in 57% of records (511,754 out of 893,578).

I can’t find a reason for why this would be. The universe of GEO3_ZA2016 is all households.

Thank you for any help!

Sorry about this! It turns out I just inadvertently included the 2011 South African census in my sample. So, of course, GEO3_ZA2016 was missing for about half of the South African records.