In some random cases, reviewer may reject your app submission by showing the problem that they couldn’t import their account in the system. It rarely happen & it’s a mistake of the reviewer that he might tried to import a wrong account that doesn’t work for app approval purpose or didn’t granted all the permission asked by the system or anything that actually unknown.
Including us & some other people faced this problem. However don’t worry about it. It’s not any problem of the script but a misunderstanding from the reviewer.
In this case we suggest to resubmit your app.Don’t worry about resubmit, you can resubmit it unlimited time without any problem.
Before resubmit, Login to the account that you have provided to the reviewer in ‘’Provide Verification Details”.
1. Try to import your own admin account there. Check if you face any problem or not.
2. Also you may create a test users from Roles->Test Users Menu. [Optional]
3. Login as the test user & import the test user account into the system. [Optional]
If all these work, then there is no problem to resubmit now.
Now during resubmit, give some extra instruction in ‘’Provide Verification Details” beside your application credential & other step.
Write some content like this to the reviewer
I have checked all and its working fine at our end but i cannot understand what happened at your end. It's all working fine for me, and I also created a test user that also fine to login. Please see the attached video about login flow & grant all permission, it must work. Also make sure that APP is in development mode, so reviewer should be able to login when APP is in development mode too.
Then resubmit & wait for the result. However you may get another rejection but keep trying.
At the final stage here is some link to contact Facebook support regarding the matter or you can open a bug report also as actually everything is fine & working for both your admin account & test users too.
Facebook Developer Support https://developers.facebook.com/support/
Facebook Developer Community https://www.facebook.com/groups/fbdevelopers/