Bug: Skin is not showing

### In which plugin has the error occurred?

FancyNpcs

### What happened?

I ran ``/npc skin docs @mirror`` but the skin is not showing

The server is running with [MultiLogin](https://github.com/CaaMoe/MultiLogin). Maybe it's the reason but I am not sure.

### In which software has the error occurred?

Paper

### Plugin version

2.8.0.308

### Server version

1.21.8

### Relevant log output

```shell
https://mclo.gs/kqayDiT
```

Start by reproducing `/npc skin docs @mirror` with FancyNpcs 2.8.0.308 on Paper 1.21.8, then review the linked mclo.gs log and check whether MultiLogin affects the result. Done means identifying the cause and confirming that the NPC skin displays correctly in the reported setup.

Written by the indexing model from the issue text.