It doesn't work

costume table content:

item_entry: 90099 (random id)
display_id: 567 (this morph id)
sound 0
scale 1
duration -1
cooldown -1

but ingame it doesn't work

Reproduce the issue using the costume table values shown, especially item_entry 90099 and display_id 567. Start by locating how costume-table entries are loaded and applied in-game, then verify whether the item and morph identifiers are accepted and whether the resulting costume works in-game.

Written by the indexing model from the issue text.