UpdraftPlus not uploading to Amazon S3

I configured my S3 account according to the instructions on this page: https://updraftplus.com/faqs/what-settings-should-i-use-for-amazon-s3-and-how-should-i-configure-my-amazon-s3-account/.

When I clicked the Test S3 Settings button, I got the message that it succeeded in creating the file, and since deletes were turned off, I found the test file in my S3 bucket.

But when I ran the backup, there was nothing added to my S3 bucket. I did get the backup files in my wp-content/updraft folder, however.

Can you help me get the backups into my S3 bucket?

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