Asset not displaying against the contact
Check in the contact, under addresses that the property is ticked as display in search. If current address send post here should also be ticked.
For a former tenancy address the display in search should be ticked with no effective to date.
Asset nor Agreement displaying against the current contact
If the contact has been ended within the contact group in error, then the contact group may show zero members. If so the contact will need to be made effective again within the group (remove the effective to date within contact groups, members tab)
Note occasionally you will need to save, close and reopen the contact group screen for it to take effect
Also check the Contact Group Details screen - ensure there are not 'effective to' dates on the page to stop it displaying.
Note it will not refresh any open current screens - instead close contact and carry out a new search to check.
Other issues can also be the address on the contact AND contact group need to be reviewed and ensure displaying correctly.