343 are going to be removing challenges that are frequently skipped or not completed by the community (deemed as too hard). While that may be frustrating right now, it will get better over time. They want lots of variety, but sometimes that means some challenges are too hard unintentionally.
There are some challenges that are broken right now they will of course be addressed, don’t worry because if you play next week 23rd-30th you will unlock the Sigil Visor anyway so there is no need to bust your butt getting it this week. Items will recycle as well if you do miss out on any so you can always obtain it again in the future.