If a Lookup field is grayed out and cannot be used, the following causes are possible.

• The user does not have permission to view the datasource app of the Lookup field.
• The user does not have permission to view the key field of the Lookup field.
• The user does not have permission to edit the Lookup field.

For the solution to each situation, see below.

One of the following settings may be the cause of the problem.

• The user has not been granted permission to view the app in the Permissions for app settings.
• The user has not been granted permission to use the app in its app group permission settings.
• The app's App group is set to Private.
• The app is in a private space, and the user is not a member of that space.

Open the App settings screen of the datasource app, then grant the user the View records permission on the Permission for app screen.
Configuring permissions for apps

Use one of the following methods to grant the user permission.

• Open the App settings screen of the datasource app and change its app group.
  Changing which app group an app belongs to

• Open the kintone administration screen and grant the Manage/use/delete apps permission in the app group's permission settings.
  Configuring permissions for app groups

The creator of the datasource app needs to change its app group to one other than Private.
If the app group is Private, only the app creator can use the Lookup field.

A space administrator needs to add the user as a member.
The steps to do so are as follows.

1. Access the space.
2. Select Manage members from the Options icon at the upper right of the space.
3. Add the user in the Members tab.
4. Click Save.

Grant the user the "View" permission for the key field of the datasource app in the Permission for fields settings.
Configuring permissions for fields

Grant the user the "Edit" permission for the Lookup field in the Permission for fields settings.