There are two usual reasons.
Your access doesn't include them
Your role, or an override on your user, limits which properties you see. Ask your company's UDP admin to check your property access in Settings > Users. An admin can only give you access they have themselves, so if your admin can't add them, contact us.
They aren't in UDP yet
A newly acquired property, or one from a PMS that isn't connected yet, won't appear for anyone. Contact us with the property's name and the PMS it's in.
[Image: The dashboard header showing the property scope line under the title]
To tell the two apart, ask a colleague with access to all properties whether they see it.