Please make sure that you have installed the following:
- VS2019 latest build.
- SQL Server Integration Services Projects extension for VS2019 v.3.16.
Do not use v.4.0 preview, or v.4.1.
- Microsoft Connector for Oracle v.1.2
When you install its 64-bit edition, it installs both 32-bit and 64-bit drivers.
And make sure that SSIS project TargetServerVersion setting value is SQL Server 2019