The retired address that never went away
The single most common cause of multi-location entity problems, the cheapest to fix, and the one nobody owns.
What happens when a location moves
The site is updated the same week. Everything else is not. The old address stays in directory listings created years ago, in press coverage that will never be edited, in a supplier page, in a professional body record, in a footer on an old landing page, and in whatever scraped all of those.
For a person this is mildly confusing. For a system assembling an entity, it is two addresses with no indication of which is current.
Why it is worse than an absence
An unlisted location is unknown. A location with two addresses is contradictory, and contradiction reduces confidence in everything else about it. A system with low confidence names a clearer competitor, so the cost is not confusion, it is absence from answers where the business would otherwise appear.
Why nobody fixes it
Because nobody owns it. The move was a facilities project, the website was marketing, the listings were created by whoever needed one at the time, and the old press is nobody. Each individual stale record is too small to escalate, and there are forty of them.
What actually works
Search for the old address, not the new one. The finding is wherever it still appears, and nobody thinks to look for the thing they stopped using.
Correct the sources you control, then the ones you can request. Directories, profiles, professional listings and supplier pages, in that order.
Leave the ones you cannot change and stop pointing at them. Old press cannot be edited. What can be removed is every internal link still sending signals to it.
Redirect properly if the old location had its own page. A location page that 404s loses whatever independent references pointed at it.
When to check
Immediately after any move, rebrand, merger, or change of business name, and then once a year. These are the moments things break, and they are also the moments when everyone is focused on whether the new thing works rather than on whether the old thing is still claiming to exist.