(ORA-12154) Unable to connect to data source in tnsnames.ora from migrated SSIS project in VS 2017

I have a directive to pull code off of an old server and move it to my workstation, and also to update all TFS connections to our new TFS 2017 setup. I found a very important SSIS project that was only maintained by the person I replaced; it was still in VS BIDS 2008, and therefore can't connect to TFS 2017. This means I need to migrate the solution. For the most part, I've done so, but it has an Oracle connection that is giving me trouble, since the original provider is no longer supported. I'm not able to resolve the name when attempting to update the connection. The error is ORA-12154: TNS:could not resolve the connect identifier specified.

What I've done so far:

• Install Oracle Client 12c with Administrative tools
• Install the ODAC and ODP.Net
• Install the SSIS Connectors v5.0 for Oracle
• Added all server entries to tnsnames.ora and confirmed the syntax of the file
• Successfully used tnsping to touch the server (20ms ping)
• Rebooted the machine to satisfy "The I.T. Crowd" checklist
• Pinged again just to make sure nothing involving network policy modified the files on reboot
• Opened the old data connection in the connection manager pane of the .dtsx editor in VS 2017 and changed to the Oracle Provider for OLE DB
• Confirmed the login is correct and the Data Source Name matches the name in tnsnames.ora
• Confirmed TNSNAMES is in the NAMES.DIRECTORY_PATH variable for sqlnet.ora
• Looked for a solution online (including here) and found that none quite apply to using the SSIS editor.

I was going to try bypassing the alias via the Data Link Properties and just pasting in the location, but there's a problem there, as well:

Also, all of the "advanced" tab is inactive. I can edit values in the "All" tab but the Location property isn't there.

I've hit that "where do I go from here" wall. How can I successfully connect to this datasource?

I found the culprit. Thank you to everyone for your assistance.

The cause was a stumbling block created in the installation and troubleshooting process. When the ODAC installed, it used a different user due to site permissions; the other location was in the system %PATH% above the correct one. By reordering the list so that the correct path to the tnsnames.ora file was on top and rebooting the system, the problem was resolved.