Who can see a record
Why two people in the same organization see different records, and what happens when access is revoked.
Records are not visible across the whole organization. Each one is granted to particular people, either directly or through a team they belong to, and you only see what you have been granted.
Access itself is set up in the web console. The phone reflects it.
What this changes on the phone
Record lists are yours, not the organization's. Two colleagues can open the same entity and see different rows. Neither list is wrong.
Record counts are per person. The number on an entity card counts the records you can see, not how many exist. Someone else's count for the same entity will differ.
When access is revoked
Opening a record is checked at the moment you open it, so a link someone sent you, or a favorite you starred months ago, fails cleanly rather than opening an empty screen.
One wrinkle worth knowing: your starred and most-used lists live on the phone rather than on the server, so a record whose access has been revoked can still appear in Jump back in until you tap it once. After that it drops out.
Getting access
Ask an admin. Access is granted per user or per team in the web console, and there is no way to request or grant it from the phone. See What you do in the web console.