Here are two tests I ran, one with Akamai headers and one without.
Akamai headers added - WebPageTest - Running web page performance and optimization tests...
No headers - WebPageTest - Running web page performance and optimization tests...
With Akamai headers, quite a few requests were not loaded and LCP wasn’t reported. There are few more things, however the gist is same. The test doesn’t work properly. For the record, these tests were scheduled using UI and headers were added under “Advanced > Custom headers”. Here is the string that was provided by Akamai.
Pragma: akamai-x-cache-on, akamai-x-cache-remote-on, akamai-x-check-cacheable, akamai-x-get-cache-key, akamai-x-get-true-cache-key, akamai-x-get-extracted-values, akamai-x-get-ssl-client-session-id, akamai-x-serial-no, akamai-x-get-request-idLink to Akamai Pragma Headers documentation: https://learn.akamai.com/en-us/webhelp/cloudtest/cloudtest/GUID-15C82BC2-4C32-47C5-837F-ED5CFCE2DA43.html