Hi. Your connection user may not have read authorization on those objects and fields. Note that in Salesforce, simply being a System Administrator does not automatically confer read authorization on all objects/fields.
See the documentation for the connection-level "Ensure field read access" setting here:
IMPORTANT: Only enable that if it's okay for IC to modify your connection user's profile to authorize it for all objects and fields! If that's not okay -- and it's absolutely not in a production org and generally not in a shared org like a sandbox -- you'll need to authorize those objects/fields explicitly.
Once that's done, regenerate the SObjects portion of the OST and it should include the missing objects and fields.
Regards,
Scott Wells