Coat a 6 or 8 quart Instant Pot with cooking spray. Make sure your ham fits in the pot, if not you can trim it a bit to fit.
Pour the pineapple juice into the bottom of the pot.
Place an Instant Pot trivet in the pot if you have one. Place the ham cut side down on the trivet, or in the bottom of the pot.
Rub the brown sugar all over the ham, then pour the maple syrup over the top.
Seal the pot, then select Manual High Pressure. Cook for 12 minutes.
Let the pressure release naturally for 10 minutes, then carefully turn the valve to manually release pressure.
Remove the ham from the pot and cover to keep warm.
Turn the pot to Saute, then bring the glaze mixture in the bottom to a simmer.
Place the corn starch in a small bowl and whisk with 3 tablespoons of water until smooth.
Pour the corn starch mixture into the pot. Cook for 1-2 minutes or until glaze has thickened.
Pour the glaze over the ham.
Optional step: If you want, you can broil the ham in the oven at this point on a sheet pan for 3-4 minutes or until glaze has caramelized.
Transfer the ham to a platter. Decorate the serving platter with fresh herbs if desired, then serve.