When the "Lookup" field is grayed out and cannot be used, possible causes are as follows.

• The user does not have the view permission for the "Datasource App" of the "Lookup" field.
• The user does not have the view permission for the Key Field of the "Lookup" field.
• The user does not have the edit permission for the "Lookup" field.

Following are the solutions for each of the situation.

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

• The user is not granted the view permission in the Permissions for App setting.
• The user is not granted the permission to use the app in the permission setting for app groups.
• Private is selected for App Group of the app.
• The app is in a private space, and the user is not the member of that space.

Open the app setting screen of the app specified as the "Datasource App" and grant the View records permission in the Permission for App setting.
Configuring Permissions for App

Do one of the following.

• Open the app setting screen of the app specified as the "Datasource App" and change the 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 permission setting for app groups.
  Configuring Permissions for App Groups

As an app creator, change the app group of the "Datasource app" to a different one other than Private.
If the app group is Private, only the app creator can use the "Lookup" field.

As a space administrator, add the user as a member.
The steps are as follows.

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

Grant the view permission on the Key Field of the "Datasource app" in the Permission for Fields setting.
Configuring Permissions for Fields

Grant the edit permission for the "Lookup" field in the Permission for Fields setting.