Short joist not continuing through kitchen soffit foiling remodel plans
Evidently you took out a wall that was used as a bearing wall for the ceiling joists that are turned perpendicular and are not connected to the intersected joist. The few that are tied to the intersecting ones are there just to control the sag of the last one so it does not put a dip in the ceiling right where the wall is that you took out. It was all supported by the missing wall.
It was never intended to be an open space at anytime as you are trying to do. Since the span is 14+' on the joists that are now unsupported, it will need to be redone with a flush beam set in the ceiling and configured by an engineer who needs to know all the particulars about attic space, snow loads, span details and ceiling joist sizes and spacing, some of which you provided, sorta.
The way the ceiling is typically framed for an open ceiling as you desire, is the predominate run of joists are run all the way to the end wall, perhaps as close as the roof rafters allow on the perpendicular roof, sometimes as much as 4' away, not the 14+' you have, which is where some of the problem lies. Then the last joist is doubled to act as a beam to hold the ends of the what would now be very short rafters going the other way. Doubling the beam is a typical detail, it may need to be tripled, depending on the overhang conditions. Hence the engineer. Besides, this is always laid out on the building plans at the time of construction, and designed or approved by an engineer before construction begins