User X unable to sudo as user Y; authentication succeeds, but execution fails

We have LDAP running in our environment. A particular user X is provided sudo access as another user, Y, but when X tries the command sudo -u Y -I, the system asks for a password. After entering the password, it throws an error, unable to execute /bin/bash as Y. Another user granted access to use sudo in the same way can perform the same action without any issue. The problem seems to be only for the X user. Also, the settings were working fine for this user, who has only recently been facing this issue.