Challenges in general in a multiplayer game have always been a pain in the ass. Usually because challenges are exactly that, challenging, not in the way that one has to tackle a difficult goal but because they are usually uninspired and force the player to go out of their way to do things they otherwise would not want to do, and in some cases not even enjoy. So when you mixed generic challenges like, play X game mode X number of times, play X character X number of times, kill X things X number of times. Along with a multiplayer team based shooter it can and probably is currently causing a variety of problems.
One, your players are being forced to do things to progress instead of playing the game the way they wanna play and see clear progression through the means of XP gain.
2, your players are being forced to player characters they might not even like, or are generally bad with. That means everyone else in their team has to put up with it or they themselves might stack that character messing up a possibly good comp, I dont know since you cant choose your character after locking in for queue not before...
C, The challenges can easily take president over the team, I mean why would I care if we win it doesn't do anything to help complete my challenges, unless winning is the challenge...
and finally IV, besides everything listed above when it comes to this particular challenge system. The dailys dont go away but they stack, meaning instead of having a set of all new dailys I cant avoid the challenges I just rather not do in general, eventually im going to be left with three daily challenges that wont go away for things I dont wanna do. Like my current 2 out of three challenges, Win heard of the hive 2 times. I dont even like playing that game mode, at least not until i get some in game comms cuz fuck discord damn it! Anyways theres my miniature rant about why I need to start tacking my anti depression medication again.