So I just ended the cutscene where I'm escorting certain fine fish folk. At the end of it, I'm swimming through air. I'm using Steam, a controller, and have the 1.2 update. This is a purely solo playthrough.
#I can swim on land.
ancient bolt
serene rose
Hello @ancient bolt . thank you for reaching out to us, and so sorry for the inconvenience! The team is aware of this issue and is actively working on a fix.
Hopefully, it will be resolved soon. We appreciate your patience while we sort this out! 
shadow aurora
Got the same bug !