Unable to get data in HCM group value sets when passing username of user by using fnd_global

Summary:

I am not getting any data when adding the following line to the query but I can get the data when I hard code the username.

U.username=FND_GLOBAL.USER_NAME

Content (please ensure you mask any confidential information):

I am using a value set for setting up an HCM group.

In the value set, I need to query by the user who has logged in.

I have tried several ways to get the username or user id as follows in the valueset but in vain

1. (SELECT u.person_id FROM PER_USERS U WHERE
   U.USER_GUID=FND_GLOBAL.USER_GUID)