Update:
There's a patch today that addresses the issue with losing relationships after entering build mode from map view.
Do any of you have tried backups of your saves yet ? Do the relationships disappear every time you start the game ?
So I checked an earlier save file and their relationships are intact. The one I was playing right before the patch is the one that's lost them.
And they get lost again if you revert to it right before the patch ? Have you sent that save to QA (before adding it back) or the one where they were already lost ?
Here are the details of my experiments. (long winded post alert!) Household 1 is two roommates, best friends with no romance, After patch they did not even know each other. I organically had them interact and SLOWLY increased friendship. Quit game and came back they were still acquaintances. I cheated their relationship to 100, quit game and then launched household 2 instead of them. Household two is large, Grand parents, parents, actual played butler and nanny, toddler and baby. No one even knew each other. However the family tree was still intact within the household. I lost distant relatives a long time ago due to my own way of moving them around so anyone wondering about family trees of people who have moved out... idk. I cheated them all back to friendship and romance levels. Quit game reentered. Both households kept their relationship levels. One thing to note, I did not have to repeat the modify relationship cheat code for both sims as I have had to do in the past. i.e. modifyrelationship Sim Two Sim One 100 Friendship_Main and then modifyrelationship Sim One Sim Two 100 Friendship_Main. Just did it one way and both were changed. I am wondering if this problem is a by product of the major relationship rework done for furry friends?!? Also even though my groups are intact their relationship and even introduction status is missing.
EA Staff@stbnchristine @Jupeycat @crinrict @solarafey @Sysomi @Stephhie13
Update:
If you are loading into an older save on the new patch, please ensure that you press Play on your active lot first; do not start by entering free-build mode on a lot. If you load into free-build mode first, you could potentially wipe all relationships in your game. If you encounter this issue make sure to exit without saving. If you accidentally save, you can use Recover Save (from the Load Game menu). Our engineers are actively investigating this issue. Thank you for your patience.
Going to mark @SimQARobo post as solution for visibility.
It's still an open issue that needs resolving quickly.
