Why can't I see the strict-transport-security header after configured

Grafana Configuration
1

Hi guys
I’m using Grafana 7.0.0 and we must enable the HSTS on Grafana

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As you can see, I have enabled these configuration settings
after restart grafana-server, I still can’t see the strict-transport-security header, but can see other headers like x-content-type-options
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Do you know how can I see the strict-transport-security header?