Enabling HttpCompression IIS 8.5 Windows Server 2012

 I am trying to enable HttpCompression for  Json files, but the system.WebServer/httpCompression is missing from the configuration editor options in IIS. I have the configuration applied in the Web.Config of my site, and it works fine in my development computer (Windows 10 - IIS 10), but when deployed to the test server it doesn't work. It doesn't work either in a development machine with Windows 7 Ultimate and IIS 7.5

These are our Web.config settings:

<httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files" staticCompressionIgnoreHitFrequency="true" dynamicCompressionDisableCpuUsage="70" dynamicCompressionEnableCpuUsage="50"><remove name="gzip" /><scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="9" dynamicCompressionLevel="4" /><dynamicTypes><remove mimeType="text/*" /><remove mimeType="message/*" /><remove mimeType="application/javascript" /><remove mimeType="application/json" /><remove mimeType="image/svg+xml" /><remove mimeType="*/*" /><add mimeType="text/*" enabled="true" /><add mimeType="message/*" enabled="true" /><add mimeType="application/javascript" enabled="true" /><add mimeType="application/json" enabled="true" /><add mimeType="image/svg+xml" enabled="true" /><add mimeType="*/*" enabled="false" /></dynamicTypes><staticTypes><remove mimeType="text/*" /><remove mimeType="message/*" /><remove mimeType="application/javascript" /><remove mimeType="application/xml" /><remove mimeType="image/svg+xml" /><remove mimeType="*/*" /><add mimeType="text/*" enabled="true" /><add mimeType="message/*" enabled="true" /><add mimeType="application/javascript" enabled="true" /><add mimeType="application/xml" enabled="true" /><add mimeType="image/svg+xml" enabled="true" /><add mimeType="*/*" enabled="false" /></staticTypes></httpCompression><urlCompression doStaticCompression="true" doDynamicCompression="true" /><serverRuntime frequentHitThreshold="1" frequentHitTimePeriod="00:00:05" />

I already ran the commands to unlock the corresponding sections:

%systemroot%\system32\inetsrv\APPCMD unlock config /section:httpCompression

%systemroot%\system32\inetsrv\APPCMD unlock config /section:serverRunTime

We have the Static and Dynamic Content Compression features installed.

What are we missing? Why is the HttpCompression option missing in the Configuration Editor of the site? Why is not compressing ourjson files on the server?

Thanks in advance!