My location does show some Census data. I3 says its "Not Available." What's going on?

As noted in What do Margins of Error indicate? the Census data is based on estimates from field surveys. When there’s not enough data available for an estimate, it gets marked as “Not Available”. For example, I know of towns where there’s a reasonable estimate for median household income, but not for the number of wireline subscriptions. That’s a part of the nature of the dataset.