Thread for new members to post their Sims 3 game issues (2020-22 version!)

Hi i have a issue with staircases (https://ibb.co/HxrPxBB)

Basically i rebuilded one of the island paradise houseboats becuase original one boat was too small and so i did however issue is sim cant use the stairs because their entrance (picture) show as blocked (there are no objects blocking it)
In the original house (which is called aquaholic) sim can use the stairs no problem but its not working on my replica is there any way to fix this?