This issue has happened to me too. It seems to be related to the bug where DLC ownership is occasionally not recognized by Steam: https://support.fatshark.se/hc/en-us/articles/360005177317--PC-Help-Why-Have-My-Items-Disappeared-
I believe restarting won’t help with the missing weeklies, but FatsharkJulia can probably put those back.
Note that favorited DLC items will get unfavorited if the items disappear due to the ‘DLC Ownership not being recognized’ bug, so check your favorited DLC items.