Azure API Management: cache-store not honoring duration - azure-api-management

Question

In Azure APIM, I have an API that queries a SQL table. I created a cache policy for the API to expire after 300 sec. I then created a script to invoke the API every 10 min, and traced the API response and SQL Server db.
For almost an hour, all calls to the API were cache hits - only two cache misses were recorded in App Insights (the first call and last call at the +50 min mark), and only two sql calls were recorded in my sql profiler trace (the first and last call).
I was expecting to see a cache-miss almost every time, but did not. Am I misunderstanding cache-store?
Here is the policy definition:
<policies>
<inbound>
<base />
<cache-lookup vary-by-developer="false" vary-by-developer-groups="false" must-revalidate="true" downstream-caching-type="none" caching-type="internal">
<vary-by-query-parameter>xxxxx</vary-by-query-parameter>
</cache-lookup>
</inbound>
<backend>
<base />
</backend>
<outbound>
<cache-store duration="300" />
<base />
</outbound>
<on-error>
<base />
</on-error>
</policies>

Answer 1

Can you please try the modified outbound policy:
<cache-store duration="10" cache-response="true" />
Store to cache
cache-response:
Set to true to cache the current HTTP response. If the attribute is omitted or set to false, only HTTP responses with the status code 200 OK are cached.
This does also mean, you have to check your current response codes 200/400/404/500/...
Maybe there was most of the time a 404 response, which was not cached.