Some tire/rim combos are a PITA and other are easy, sounds like you have the former. A few ideas:
Lay the wheel sideways on a bucket to help the tire sit uniformly on the rim.
Make sure the carcass is over the valve hole so the air is going into it.
Counter to point 1, You may need to massage the tread a little bit in various places (here’s where having 5 hands helps) to help get the bead near the hook and retaining air. You could also try to loop a long bungee cord around the tread to compress the bead outwards.
If you keep feeding it air and messing with it, eventually it will take.
Edit: also try to get the beads outward a bit, that’s where they ultimately need to be to start holding air. With the beads in the center channel there’s too much gap and the air is lost just as quickly as you’re putting it in.