This is probably because you do not have view permission for the Created datetime field.

In the Search All Contents, Search in Space, and Search in App, search results are sorted by "Created datetime" by default. Therefore, if you do not have view permission for the Created datetime field, the sort cannot be performed properly and the expected search results will not be displayed.

Try one of the following solutions.
Configure permissions for the Created Datetime field
Select "Relevance" in the "Sort by" Section on the "Search Results" Screen
Use the Filter feature in the View (If you know which field contains the value you want to find)

1. Click the App Settings icon (the gear-shaped icon at the upper right of the app's top page).

2. Select the App Settings tab and then click Fields under Permissions.

3. Click Add Permission Set and then select the "Created datetime" field to set permissions.
   
   Example

   Management Department	[✔] View	[✔] Edit
   Everyone	[  ] View	[  ] Edit

   In this setting example, the Management Department members will be able to view and edit the Created datetime field. Other users cannot view the returned records when the search results are displayed with the default Sort by setting.

4. Click Save at the bottom right of the screen.

5. Click Update App at the upper right of the screen.

6. On the confirmation dialog, click Update App.

The permission setting is applied to the app.

1. Open the target app, enter the keyword in the search box on the upper side of the screen, and perform the search.

2. On the upper right side of the "Search Results" screen, select Relevance in the Sort by section.

3. Change the value for "Created by" and "Created Date Range" if necessary and click Search.

If you already know which field contains the value you want to find, you can also use the Filter feature to find records.

For more details on the Filter feature, refer to Filtering Records to Display in the View.