Sonarr gets the path from SAB’s history and moves it to the folder that was set/chosen when the series was added.
Watching a folder and importing is unreliable because files can be moved prematurely, before they are completely extracted or moved from another location.
Docker paths can cause issues because the path mounted for SAB’s output folder might not map where Sonarr sees the files.
Also make sure you’re using a category with SAB and its configured in Sonarr, without it things don’t work as smoothly.