I see you have a double :: in the first occurrence you mention it, unsure if that's a typo.
If in Access Tracker the attribute is set in the Computed Attributes, I normally copy it from there to make sure I don't have any typos; then add %{ in front and the } after it (no spaces).
Had a few times where there was a very small difference. Or the enforcement was triggered on a non-TLS authentication, so the attribute was not set. And you in the enforcement you may need to check if Certificate:Not-Valid-After is actually set before you trigger the update endpoint enforcement.
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Herman Robers
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