Doesn't let me add custom tiles

[GameOnitay]

Describe the bug

when trying to add a new tileset, it doesnt let me add the background, its just locked https://imgur.com/ZEt3Lht

Reproducing steps

open a room
making a new tileset
doesnt let me put a background

Setup Details

latest UTMT
in windows
idk wym by gamemaker version but latest

[CST1229]

you're dropping a string with the name of the background in, not the actual background itself (located under "Backgrounds and tile sets")