I had same few days ago and i tryed something yesterday that i think fixed it for this one until the next one... (still not normal this happen and that we have to use any cheats to fix every of them one by one...)
I actually play household of Half Sister of Cassandra Gothik. Cassandra passed away 2 sims days ago and her half sister and all household had phonecall notification of her death each time i opened my save and each time i went in CAS and go back in game and it reset every sad things to 2 days again and again for everyone in my household... It made me going crazy...
Yesterday i tryed something, i decided to take control of the Gothik Family (where Cassandra should be...) and play with them. I used testingcheats on, click right on her tomb outside in the garden, add her ghost to the family... But when i did she did not appeared as ghost but as old human not died yet who was almost to die in the day like she was stuck and did not died properly... Then i click right again using cheats and obliged her to grow old, like she was already old she died of course, it was the point to make her to die correctly, and in that time Grim came and on my control the death was normal, she turned as ghost, and i valided her to play as ghost. Her 1st tomb got removed automatically and replaced by new one... Seems all was fine as normal death...
I left this family and turned back in mine with her half sister and finally for now no more phonecall about Cassandra death, like it fixed it...
I think the bug make the sims to dont die properly like it should and that is why they appear as human instead of ghost in family tree and friendlist and why we keep have phonecall and notification about them to die again and again...
Im playing a legacy challenge only generation 2 and so i just start to have family who die one after another so i will see how its going for the next who will die and if what i did with Cassandra keep work for others until they fix the bug about sims who dont die correctly.
I hope it can help people to be less annoying by it until they fix it in the game. I will say if it the bug continue and if i can fix it the same :)