Sim can go downstairs but can’t go back upstairs

My sim can walk down the stairs but can’t go up the stairs. She’d wave her arm with the thought bubble saying something is blocking the way. There is nothing in the way, there is enough room for routing because she was able to use the stairs to go down. I haven’t had this issue before and not sure what else to do. I tried deleting the stairs and placing another one down yet still the same issue.