My DM granted me an item that I'm trying to replicate on D&D Beyond.  The basic idea is that it's a horse heart that when eaten Game of Thrones style (assuming you can stomach it), it grants you a permanent increase to your hit point maximum.

I believe I went through the correct steps to create this item with the creation tool, but it isn't applying the HP boost.  My character is a level 3 fighter with 22 HP - the item should bump it up to 27.

Here are pictures of the Item and it's non-effect on old One Leg.

Any help would be nice.  Even though the item is eaten/disposed of, I'm okay with keeping it in my inventory to keep the bonus in effect, so long as I don't need to use a slot to attune to it.

Probably easier to edit the character and put a 5 in HP modifier.

That's what I did to begin with, but I switch back and forth between my computer and my phone, and every once in a while the 5 disappears from the Bonus HP field.  I was hoping to just have a permanent buff applied via an item instead to ensure that it stays.

Not as bonus HP, because that disappears after rests. In the editor, under class, click manage HP, and put a 5 in HP modifier. This will stay.