Missing spell in homebrew creation

Maybe I'm a crazy person, but the cantrip Swordburst is available in the app, but I can not add it to an item or a custom feat. I own the book, have two characters with the spell, but it's not in the list when I'm trying to make an item or feat. 

Are you sure you actually own a book that includes it (the Sword Coast Adventurer's Guide or Tasha's Cauldron of Everything) and don't just have access to it through content sharing in a campaign?

If you only have access to it through content sharing, you won't be able to use it in homebrew content.

Also, at the risk of stating the obvious, it's called Sword Burst, with a space, so if you search for "swordburst" you will not find it.

Yes, I own the book. 

And good call, but I was going through alphabetically, rather than searching the name.