Sims in family tree keep turning into Unknown Sims

Mine is randomly doing this also with NPC sims. They are there one day I play and then next the 3 or 4 sims will be unknown. 

Since the recent family tree update, Sims in my legacy save are being incorrectly labeled as “Unknown” in the family tree. This issue is progressively getting worse over time.

I have a large, multi-generational household (approximately 8 generations), and many deceased Sims are no longer properly displayed. Instead, they are either completely missing or replaced with “Unknown” placeholders in the family tree.

This is still happening randomly without any reasons even I played the new save since the R&L launch day patch. The eldest ancestors in my game suddenly got unknown single parents each of them. The newly created sim who married with my dynastic family got unknown dual parents. They messed up the family tree. 

I really want to know how to delete these Unknown sims. Or more creative solution, hide those unknown sims on the family tree or using Forge family tree feature to replace unknown sims with any sims.

I find Skilful Sleep from BH pack generate the unknown parent for single parent along with the temp ghost sim. even I deleted localthumbcache file to troubleshoot, the unknown parent persistent. this is prolonged issues since BH.

has this been resolved yet?? 

https://forums.ea.com/idea/the-sims-4-bug-reports-en/bh-skillful-sleep-projection-in-family-tree/12026543

other than that, the unknown sim cover another sim on my family tree. this might be the reason why it looks like a sim turned in to an unknown sim but it doesn't, it covers another sim on the family in an exact position. 

Hello all,

If any of you are still encountering this on the latest game version (without mods), would you be willing to share your save file(s)?

If so, please send me a private message with a link to the file. Instructions can be found here: https://forums.ea.com/idea/the-sims-4-bug-reports-en/information-how-to-send-user-files-to-the-sims-4-team/5048472

Thanks!

I patched my game and tested it without mods, my sim and his husband are still brothers and still have an unknown parent. Additionally, their third partner now has a set of unknown sims as parents. This is my legacy save but it is only on two generations. This bug is affecting the first generation sims, these are sims I made to start the game so they don't have pre-existing family.