Reapers Rewards week 6 broken

That file should be right there when you open the Sims 4 folder, beneath the row of sub-folders such as cachestr, configoverride... actually, it should be the first file after the Tray folder. The second file should be the avatarcache.package. Removing both can fix the event, and the game will automatically create new versions of those files so moving or deleting them doesn't do any harm.

It's what worked for me, so it might be worth a shot. And in case you only get the Grim icon but no tasks after removing both files - give it a few seconds. In my case, a popup showed up after a few seconds, telling me to wait for the newsletter. After that, it was pretty much smooth sailing through the rest of week 3 and weeks 4 to 6. Occasionally, the plumbobs would disappear for a second or two after completing a task; then a short message told me that the gnomes were working on the problem, and a second or two later, the event was back up.