Nobody in my guild that I've spoken to has been able to inflict a single weapon poison hit for today's daily endeavor and the audio and visual cues for equipping a poisoned weapon are also missing. And in my attempts to inflict weapons poisons I have not see any of the usual poison leaking from corpses.
Yes, weapons poisons are working on my alt account, I'll go back to my main account later and see if I can figure out why it wasn't working there and post here if I find a solution.
One thing I do when this sort of endeavor comes up is to attack enemies using only light attacks.
This means it usually takes longer to kill enemies, thereby increasing your opportunities to apply your weapon poison to them.
Also, I'm not sure whether weapon poison can proc from using skills, so avoiding the use of skills and using only light attacks ensures that you're using attacks which definitely have a chance to proc your weapon poison.