My archon stopped working when I switched to 6piece Firebird, however, when I had 5 piece firebird, and 2 piece Vyr, I could use Archon with ease.
Tested Further: Archon Teleport appears to be my problem, I switched back to Archon Combustion.
2nd Edit: I strongly advise finding a build which allows use of 2 piece Vyr, for all runes of Archon, rather than having no teleport while in Archon with the 6P Firebird.
--Side note: I also used Phelon's trinity settings, whether that had effected it or not, I shall not know.
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Final Test: Have Teleport OOC ticked, this will allow Archon to be used, if you've selected the Teleport 2nd rune on Archon.