Firefox custom metrics

[Vlad_M]

Greetings,

I have a private instance of WPT Service running version 18.10, along with Linux agents that also run 18.10.

I am able to retrieve custom metrics from tests on Chrome at test time. I do it by extracting those from js, like that:
-----
[atf]
return newrelic.info.jsAttributes["atf"];
.
.
.
-----

However, it seems that those same metrics can't be retrieved by firefox. I was wondering whether the behaviour is different between two browsers and what might be possible causes of that