OracleConnection not detecting Oracle Client in BIML Express

Question

I'm trying to establish a connection (using Bilm) with an Oracle database using the OracleConnection and OracleSource objects in BimlExpress for Visual Studio Enterprise 2017 using the following Biml script:

<Biml xmlns="http://schemas.varigence.com/biml.xsd">
    <Connections>
        <OracleConnection
        Name="oracleConn"
        ConnectionString="Data Source=XXX.XX.XX.XXX:XXX/XXX; User Id=XXXX;Password=XXXX;Integrated Security=no;"/>
    </Connections>
    <Packages>
        <Package Name="package1" ConstraintMode="Linear">
            <Tasks>
                <Dataflow Name="obtain data">
                    <Transformations>
                        <OracleSource Name="load table" Connection="oracleConn">
                            <ExternalTableInput Table="table1"/>
                        </OracleSource>
                    </Transformations>
                </Dataflow>
            </Tasks>
        </Package>
    </Packages>
</Biml>

However, when I try to run the validation in Visual Studio this message shows up:

Validating Biml
Error   0   Oracle Client Access not detected. Install the 32-bit or 64-bit version of Oracle Client Access that matches your version of Biml/BimlStudio. Biml Validator threw an exception attempting to validate your package. Exception type: InvalidOperationException      0   0
AstValidator. There were errors during compilation. See compiler output for more information.

I already have the Oracle client installed along with the Attunity connectors for Oracle found here and have used them for projects not involving Biml (obtaining tables from Oracle in Visual Studio using the connectors). So I really don't know what the problem could be other than Biml somehow not being able to access the client. Is there a way I can debug this or is there some known fix for this?