Provisional headers are shown error when first time logging in

Question

I am having this trouble for one specific call that I am making with my angularjs app.

Here is step by step what is happening:

1. I login to my angularApp

2. Go to this page where I add a subOrganization (where error happens)

3. I put a name for my subOrganization and click "add subOrganization".

4. this following function is being called when adding new subOrg:

    addSubOrg: function(newLocation,parentLoc){
        return $http({
            method:'POST',
            url:'https://xxxxxxxxxx.net/xxxxxx/Organizations/'+$cookieStore.get('account')+'/Services/AddOrganizationalUnit?appKey=' + $cookieStore.get('keyId'),
            headers: {
                'ACCEPT':'application/json',
                'Content-Type':'application/json'
            },
            data:{
                name:newLocation,
                parentName:parentLoc
            }
        }).then(function(response){
            //console.log(response);
            return response;
        },function(err){
            console.log(err);
            return err;
        })

5. It gives me this "Provisional headers are shown" message and kicks me out of the site.

6. I login back in again and apply the step 1,2,3,4 again and it works perfectly fine.

I tried to read this link very carefully but what I don't understand is 1. why does this only happen when first time logging in? 2. why does this specific call give me error even in the beginning when rest of 60 other calls are working fine.