I completed the 3 chest triumphs a loooong time ago and the fix they implemented did not work for me back then. I stopped playing Destiny 2 for some time and after returning I've tried collecting all the ascendant chests again multiple times on the same character on 3 different curse weeks, and even did shattered throne to get the 6 chests in there to see if it would help, but nothing does. The triumph just won't complete for me.