The reason why this happend is , you didnt add any skull for any lootbox
so if you have a bug like this or flying chests or game crashes :
The fix is really easy , just run the command :
/lootbox
go to edit menu , click on every lootbox you created and add a skin for it :
you can do this by going to this amazing website it provide you with everything!:
https://minecraft-heads.com/custom-heads/search?searchword=loot
but remmber to edit the link to this ->
http://textures.minecraft.net/textu...1f9a99f4ad9a73f1d2b1fe7bc46bacc4143151d506e07
it will be http and not https ..
you need to do this step for every lootbox , after you finish restart the minecraft server
and run this command :
/skyadmin purge :
if this does not work for you stop the server ,
after you create your lootbox and make sure to set the preview lobby location or the lootbox will not be saved, go to the /lootboxes folder , and enter your lootbox file :
put the link manually in here :