Unexpected Error: Couldn't load the model schema using DirectQuery with Oracle data

Hello,

Upon trying to connect to an Oracle database using DirectQuery, I encountered an Unexpected Error: Couldn't load the model schema. 

But when tried thesame source to import option, it is working without any issue.  Getting error for DirectQuery method.  Have provided the log below and would appreciate help on how to resolve the error. Many thanks in advance.

Feedback Type:
Frown (Error)

Timestamp:
2019-04-09T17:13:06.0959177Z

Local Time:
2019-04-09T13:13:06.0959177-04:00

Session ID:
51b6aac5-bd24-459e-8f3e-cb463c15691f

Release:
January 2019

Product Version:
2.65.5313.1562 (18.12) (x86)

Error Message:
Couldn't load the model schema.

OS Version:
Microsoft Windows NT 10.0.16299.0 (x64 en-US)

CLR Version:
4.7 or later [Release Number = 461308]

Peak Virtual Memory:
1.44 GB

Private Memory:
392 MB

Peak Working Set:
422 MB

IE Version:
11.1029.16299.0

User ID:
bd0eace4-0c36-4f7a-bc20-40eae68d67a6

Workbook Package Info:
1* - en-US, Query Groups: 0, fastCombine: Disabled, runBackgroundAnalysis: True.

Telemetry Enabled:
True

Model Default Mode:
DirectQuery

Snapshot Trace Logs:
C:\Users\adcgnx5\AppData\Local\Microsoft\Power BI Desktop SSRS\FrownSnapShot1531878198.zip

Performance Trace Logs:
C:\Users\adcgnx5\AppData\Local\Microsoft\Power BI Desktop SSRS\PerformanceTraces.zip

Disabled Preview Features:
PBI_shapeMapVisualEnabled
MIntellisense
PBI_SpanishLinguisticsEnabled
PBI_PdfImport
PBI_ColumnProfiling
PBI_variationUIChange
PBI_PythonSupportEnabled
PBI_showIncrementalRefreshPolicy
PBI_showManageAggregations
PBI_FuzzyMatching
PBI_EnableWebDiagramView
PBI_improvedFilterExperience
PBI_qnaLiveConnect

Disabled DirectQuery Options:
TreatHanaAsRelationalSource

Cloud:
GlobalCloud

DPI Scale:
125%

Supported Services:
Power BI Report Server, Power BI

Formulas:

section Section1;

shared T_DATE_REFERENCE = let
Source = Oracle.Database("IP Address:Port_no/service_name.com", [HierarchicalNavigation=true]),
SYSTEM_ANALYTICS = Source{[Schema="SYSTEM_ANALYTICS"]}[Data],
T_DATE_REFERENCE1 = SYSTEM_ANALYTICS{[Name="T_DATE_REFERENCE"]}[Data]
in
T_DATE_REFERENCE1;

Thanks,

Rohith