Re: Sims 4. Imperial stairs not working

@Moonlight_829   Apologies for the delay!  I did some testing and now I don't think it's the platform height but the 2nd floor railing / fence that is the issue.  From your image, is that a complete fence enclosure on the 2nd floor?

If so, try removing the stairs and then use the sledgehammer to delete the bits of fence located where the top of the stairs would be.  Like this...

(Btw, deleting those sections of fencing may also delete the ceiling above the staircases.  You can draw a room above that to add a ceiling/floor and then delete the walls and ceiling of that room; this would be to just enclose the upstairs area again.)

Then add the stairs back...

Once I did this, my sim was able to walk up to the second floor...

Please come back and update if this worked for you or not.