I don't know if this is known behaviour or not, but missions do not renew. When missions end, there is no new missions. Until something on server resets. Then missions appear again. I don't think this behaviour is known to developers.
Missions are BUGGED.
Persisting missions are always working.
Seems like that the "assigner" of missions is broken.
I think it's a bug because earlier this season this didn't exist. Missions were working always.