Referring to their GitHub, this was fixed in 1.16.7 by adding the recipe via KubeJS
At
\kubejs\server_scripts\recipes.js, add
// wool
event.shaped(
Item.of('minecraft:white_wool'),
[
'AA ',
'AA ',
' '
], {
A: 'minecraft:string'
}
)
If you are not sure how to add it, backup the file before.
Or download the 1.16.7 modpack build and overwrite the recipes.js in your server and the client modpack at \kubejs\server_scripts\