Unable to get notebooks of a sharepoint site

I am trying to execute the following graph API request against one of our customer's sharepoint site.

GET https://office365.us.vadesecure.com/safeproxy/v3?f=9mF87uEhaQ-gvaWHI8O3gogEXHoDEduYq2nmjlS1ZLGTOBJaiEyoEgINv7zjnlLu&i=5RLNnxC-Lq226sYznzp1Hp8-4RS64iQvzZBTdbXrwO1Ps9rm_4vDLqECithhcyAuEb-8eUlK-_beeKgzyoEtgA&k=gKjE&r=cm4NK-wWipDxnyh-uD3CCztS9nsCDiDzaseW_9K8bM_O-zU4JXgj9tHy6K6gOh9K&u=https%3A%2F%2Ftracking.cirrusinsight.com%2F5c9e9cdc-4047-406c-9a55-96a184081614%2Foffice365-us-vadesecure-com-safeproxy-v38

But ending up with the below response.

{

"error": {

"code": "10013",

"message": "One or more of the document libraries on the user or group’s OneDrive contains more than 20,000 items and cannot be indexed for querying using the API. Browse to this page for more information: https://office365.us.vadesecure.com/safeproxy/v3?f=HQV0yaT_IRk54S9YKtelRWoHr1JMB-aV-6SSuQGkTIKSSgKITd4WRUx2dPXyIdxq&i=5pj-00XsG9AYtr-2QlHDoHsno7SnzZUWkrpTL73mcsfe3vOUiBl8Ct_lDr3yKD4YZht2Hl3TfWky4cIGb6qTCw&k=j9Xn&r=RscOKuvtSE83ujlQr_do4UBQS4W25QswDVZBjNgTzIk7_hY4_5A_2ualOZ_XcjpW&u=https%3A%2F%2Ftracking.cirrusinsight.com%2F5c9e9cdc-4047-406c-9a55-96a184081614%2Foffice365-us-vadesecure-com-safeproxy-v37",

"innerError": {

"request-id": "f22a0847-ecf3-4ae6-886d-e8826c0bf8c2",

"date": "2019-07-30T04:57:17"

}  

}

}

Based on the link provided we have reached the customer with the workaround but they said they don't have such a number of items under their sharepoint site. The attached screenshot is provided by the customer.