REST api to un enrol LTI user is not working

Hi All

Need help in solving my issue

1. User created using Publish as LTI tool is not able to unenroll using REST API enrol_manual_unenrol_users

2. Unenrolling LTI user from course using API enrol_manual_unenrol_users is not working and it is returning null.

3. many of the moolde rest apis are returning null when it is success.

I am using moodel 3.8

thanks in advance.