Oracle connection error: Object reference not set to an instance

My support ticket still remains unresolved, I still cannot connect to Oracle DB with 64-bit PBI desktop. Since I managed to get the on-premises gateway working, here's the partial solution, 

Power BI requires the Oracle Data Provider for .NET 4 (unmanaged driver) in order to be able to connect to an Oracle DB. If you want to reduce installation size, you may use the Xcopy package, just pay attention to the installation instructions. (At first, I neglected to put Oracle installation directory to PATH, which is why my gateway did not work.) After the driver is installed and configured, just restart PBI desktop or on-premises gateway service, so that the environment variables are refreshed and Power BI is able to locate the freshly installed driver.

This is not the case with 64-bit PBI desktop, however. It seems to be a unique snowflake in a sense, that it does not use PATH for locating the driver. I believe it requires the driver to be installed in GAC - basically a directory for shared DLLs and other assemblies located under %WINDIR%\Microsoft.NET\assembly. When Oracle universal installer prompts whether to place the driver in GAC and configured on machine level, select yes. If using Xcopy version, use configure.bat in Oracle install directory to place the driver there.

When the driver is not in GAC, 64-bit PBI desktop gives me ‘System.Data.OracleClient requires Oracle client software version 8.1.7 or greater’ error. After it is placed there, I get the all too familiar ‘Object reference not set to an instance of an object.' exception. Am I still missing a step somewhere?