Can confirm this happening when the head meta hasn't display name.

my staff say the skin of head lost after reboot can you check this pls?

ok with some tests now the custom head appear to be work maybe this head is bugged, maybe we given this head before the latest build and she bugged because if we regive this head she work fine. :|

i tryed with anothers heads and its work i dont know what happen with this head :|

normal heads works but not custom

Cannot reproduce this on a spigot build that has been built today (11.02.)
It's an issue on your side

no the skull skin is obtained when we not use it on a entity and i not have any error about that in the log. This appeared in the last build.

*Check your serverlog for

com.mojang.authlib.exceptions.AuthenticationException: The client has sent too many requests within a certain amount of time

exceptions.
Your server probably sends too many requests so the uuid for the skull can't be obtained.

Open a thread with more detailed information about your plugins, especially plugins that are dealing with uuids/playerheads

https://www.spigotmc.org/forums/spigot-plugin-help.42/

and in the hand to the skin not work apparently

damn i writed to fast: skull on armorstand not work anymore and my staff said that not work on all entities.