Facebook graph api groups_access_member_info permission

Question

I have install app to private group, after app preview app has following permissions:

1. groups_access_member_info
2. public_profile
3. email
4. Groups API

After app installation to group I'm able to call groupID/feed and I can see posts and comments that I have made (I'm group admin) including my user object. My goal is to see which user made comment with its id, name etc. In access token debugger it has all permissions. App is already in live mode with Business Verification. I tried to find answer in documentation but according to documentation app has all required permissions.I also tried to remove and install app again to group but it works the same way.

Is there any way how to deal with this issue ?

Thanks in advance