Hi @Thaddy187,
We have performed testing on this issue and determined that charcoal will not transfer from the first slot of the Hobobarrel output. If you cook meat and leave that meat in the first slot which forces it to put charcoal into the second slot then it will transfer.
This is only a workaround solution but may shine a light on the core of the issue.
Let me know if it helps.
Regards
Phoenix
[AU] Survival