How do I add homebrew/specific magic items to my character sheet?

For some reason I'm only able to add base or common named items.

I've tried looking up homebrew items, but nothing turns up, even though I've been able to look them up in the past

specifically one I created:
https://www.dndbeyond.com/magic-items/8390594-blades-of-the-morning-star

in order to equip it to this character:

https://www.dndbeyond.com/characters/123647344

But for some reason I seem to be restricted regardless of what I allow on the character settings. Please help.

That weapon is based on a greatsword. That character is a rogue. Rogues are not proficient with Greatsword. Please refer to the General Homebrew FAQ, question #5 for the solution: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/131411-a-homebrewers-how-to-faq#GeneralHomebrewFAQ&BasicTroubleshooting).