@MandiisLoveCan't see video, but L-shaped stairs shouldn't have a problem with a corner. Have you got MoveObjects on? Because sometimes doorways or even lights can interfere.
And sometimes just going out to "Manage Worlds" and returning makes stairs behave.
I had no objects around the stairs at all. It was just the shell of a house. I even deleted the rooms above to ensure ensure walls were not interfering. I will try to repost the video. I had to open on my computer with windows media player otherwise I couldn't watch it. I did not have move objects on, tried again after turning it on but no success.
https://1drv.ms/v/s!AvL4KUbc3_wLgrRynbS2dCLRjv6w1g
If this link doesn't work, try opening into windows media player. If not I will need to recapture the video or change the file type somehow...
No I had no platforms on the lot at all the foundation was raised 2 notches. If I lowered it into a "sunken platform" 2 notches to the ground level it would place but deleted when I raised the platform to foundation level.
