This thread is resolved. Here is a description of the problem and solution.
Problem: 404 errors on translation page
Solution: Issue due to Yoast Multilingual 1.0.2 Updating to Yoast Multilingual 1.0.3 resolved the issue
Relevant Documentation: https://wpml.org/errata/yoast-seo-multilingual-causes-404-on-secondary-languages/
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