- The two visitor lists don't add up
- They count different units — people versus browsers. See Why the two lists don't add up.
- Old rows have no pages, device or country
- Per-person facets are computed from a recent window of events. Over a long range on a busy site, older rows fall outside it. Narrow the date range.
- Country is empty
- Country comes from edge request headers. Running against a local development environment, those headers are absent and the column is blank for everyone.
- A contact has no activity at all
- Either they were imported and have never visited, or their events have aged out under your retention setting. Retention deletes events but keeps the person.