The reason why the new challenges are not working is because epic intentionally changed the weekly challenge date to thursday starting this week. You can start the week 5 challenge sheet thursday 05/31.
KNOWN ISSUE: Week 5 challenges available in 0 seconds.
Week 5 challenges will be available on 05/31 at 4am ET/8am GMT.
This was an intended change to push back Weekly Challenges to Thursdays.