I haven’t tested this recipe with a different type of oil because coconut oil is really the best to use for the IP. It will be in solid state and it will melt once the IP is hot.
Be sure the kernels are in an even layer. They need direct exposure to the heat source so they can heat up and cook evenly.
Just like stovetop and microwave versions, there will always be a few kernels that just won’t pop! So don’t wait and remove them as soon as the popping sounds slow down. If you wait for all of the kernels, you’ll end up burning the popcorn.
If you don’t have an IP glass lid you can use any glass lid that fits. Or, try using a glass pie plate.
I think popcorn is best freshly made, but you can store any leftovers in an airtight container or ziplock bag. If it’s coated with butter, it won’t keep as long, so keep that in mind.