There was already a whole thread on it but it's been merged into the issues after patch thread here:
https://forums.thesims.com/en_US/discussion/983513/issues-after-patch/p2
Answers HQ bug report here:
https://answers.ea.com/t5/Bug-Reports/WORKAROUND-Open-staircase-cause-routing-failures/m-p/9717351#M160498
Also has anyone else found that toddlers can't use stairs anymore at all? Since the patch my toddler sim won't go up or down any stairs, even with stairs that work for adult sims so they're just stuck on one floor unless I teleport them down.
