Hi Ali,
I am on FF v45 and I haven't been able to get it to work. Alternatively, you can use the following in the console to do the same thing:
enable staging library in production
localStorage.setItem(‘sdsat_stagingLibrary’,true);
enable debug mode
_satellite.setDebug(true);
There is a cheat sheet you can download on Jim Gordon's blog here: http://jimalytics.com/tag-management/dynamic-tag-manager-dtm-cheat-sheet/
Hope this helps,
Tacia