There are multiple root causes for the excessive Primary Password prompts. So far, none of the causes I have discovered are related to Bug 1612258, so I am going to remove that bug from the "Regressed By" field (though I can't yet explain why it does appear to be the regressing bug on Windows 10 only). I am going to address the biggest root cause in this bug, and I will file another bug to fix the other known root cause and link it here shortly.
Bug 1659655 Comment 10 Edit History
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There are multiple root causes for the excessive Primary Password prompts. So far, none of the causes I have discovered are related to Bug 1612258, so I am going to remove that bug from the "Regressed By" field (though I can't yet explain why it does appear to be the regressing bug on Windows 10 only). I am going to address the biggest root cause in this bug, and I will file another bug to fix the other known root cause and link it here tomorrow.