Selling Fractional not working

[DaniCoimbra]

With updates to allow fractional to be executed, I am able to post a fractional MKT buy. But when doing a fractional MKT sell, it gives me:
{'msg': 'Fractional shares trading is not available for closing a position which is a whole share.', 'code': 'trade.webull.FRACT_NOT_CLOSE_INT_POSITION', 'data': {}, 'success': False}

I have validated that this is possible on the website/mobile. So I wonder if the API must be updated to reflect the actual endpoint.