Hello,
When using force:source:push for pushing a custom with <externalSharingModel>Private</externalSharingModel> into a scratch org with "features": [ "Communities", "ExternalSharing", "AuthorApex" ]  it "succeeds".  However the object does not reflect the proper external sharing access.  Thus the ObjectsName__Share object is not available to subsequent APEX classes that may be using.
I've posted a simple example project in bitbucket here that have simple reproduce and work around instructions in the Readme.md.

Has anyone any insights into whether I am missing some critical Meta data / XML?
Thanks.

Here is the SOAP login envelope I am stuck on:

<Envelope xmlns="http://schemas.xmlsoap.org/soap/envelope/">
    <Header>
        <LoginScopeHeader xmlns="urn:partner.soap.sforce.com">
            <organizationId>00DJ0000003L9lt</organizationId>
            <portalId>[string?]</portalId>
    

Where do I find our Portal ID?