Network private endpoint connection failed with response status 200

> ### `az feedback` auto-generates most of the information requested below, as of CLI version 2.0.62

**Describe the bug**
A clear and concise description of what the bug is.
```
urllib3.connectionpool : https://management.azure.com:443 "GET /subscriptions/0b1f6471-1bf0-4dda-aec3-cb9272f09590/providers/Microsoft.Network/locations/eastus2euap/operations/21301e17-e729-4d56-93f6-b63565f8bf92?api-version=2019-11-01 HTTP/1.1" 200 None
msrest.http_logger : Response status: 200
msrest.http_logger : Response headers:
msrest.http_logger : 'Cache-Control': 'no-cache'
msrest.http_logger : 'Pragma': 'no-cache'
msrest.http_logger : 'Transfer-Encoding': 'chunked'
msrest.http_logger : 'Content-Type': 'application/json; charset=utf-8'
msrest.http_logger : 'Content-Encoding': 'gzip'
msrest.http_logger : 'Expires': '-1'
msrest.http_logger : 'Vary': 'Accept-Encoding'
msrest.http_logger : 'x-ms-request-id': '9d246715-ef7b-4a71-9d04-12639ae10d7f'
msrest.http_logger : 'x-ms-correlation-request-id': '4e1f3bdb-218c-46d1-9fee-17f68685693d'
msrest.http_logger : 'x-ms-arm-service-request-id': '48ca286b-b91d-42e6-90eb-5fb301ef04ea'
msrest.http_logger : 'Strict-Transport-Security': 'max-age=31536000; includeSubDomains'
msrest.http_logger : 'Server': 'Microsoft-HTTPAPI/2.0, Microsoft-HTTPAPI/2.0'
msrest.http_logger : 'x-ms-ratelimit-remaining-subscription-reads': '11999'
msrest.http_logger : 'x-ms-routing-request-id': 'AUSTRALIAEAST:20200228T073647Z:4e1f3bdb-218c-46d1-9fee-17f68685693d'
msrest.http_logger : 'X-Content-Type-Options': 'nosniff'
msrest.http_logger : 'Date': 'Fri, 28 Feb 2020 07:36:47 GMT'
msrest.http_logger : Response content:
msrest.http_logger : {
"status": "Failed",
"error": {
"code": "InternalServerError",
"message": "An error occurred.",
"details": []
}
}
```
**To Reproduce**
Steps to reproduce the behavior.
Run `az network private-endpoint create` with same parameters twice

**Expected behavior**
A clear and concise description of what you expected to happen.

**Environment summary**
Install Method (e.g. pip, interactive script, apt-get, Docker, MSI, edge build) / CLI version (`az --version`) / OS version / Shell Type (e.g. bash, cmd.exe, Bash on Windows)

**Additional context**
Add any other context about the problem here.