I can confirm this as well, I was just helping out some lovely people with their Relic Quests and noticed my Hotbar wouldn't quickly change to my next set when I normally pop the LB as soon as I hear the chime, ended up doing something else and initially thinking "Did I rearrange my Hotbar or something"... nope SE either messed up a variable in the UI with Patch 2.16 or they're about to come out and say it's "working as intended"... I hope to god it's not the latter because I absolutely cannot do high level fights like this.