Sounds like you might have the side support lines run incorrectly perhaps? (see this video for details)
https://www.youtube.com/watch?v=lp-AG_dMEUU&t=149s&ab_channel=Hobie (see at the 2:20 mark of the video for this detail)
If your lines go to the front then it's going to be the old style - if you have them wrapping under it's the new style - just make sure both sides are run the same direction or they'll be shorter one side to the other. If you're still finding trouble take the seat to a dealer for help directly:
https://www.hobie.com/dealers/