dbms_cloud.copy_data gives ORA-20404: Object not found

Summary

Following "Oracle by Example" tutorial yields above error.

Content

On this page:

https://www.oracle.com/webfolder/technetwork/tutorials/obe/cloud/atp/obe_loading_your_data_into_autonomous_transaction_processing/loading_your-data_into_autonomous_transaction_processing.html

step 4 Copy data from object store to ... database ...

yields the following error:

ORA-20404: Object not found - https://swiftobjectstorage.us-ashburn-1.oraclecloud.com/v1/xxxxxxxx/tutorial_load_atpc/cust1v3.dat

(I redacted my tenant name, here and in the code snippet below.)

My console confirms that all 10 files (including the one for which I have shown the error) are stored as objects in the tutorial_load_atpc bucket. All 10 copy_data operations failed with the same error. And, everything prior to step 4 worked perfectly (as best I can tell).