So I unintentionally killed the wandering trader and its llama started spitting on me. Then, I sat on the llama by right clicking it and tamed it. It even gave me the "Best Friends Forever" advancement. It's tamed but it continued to spit on me?

What I expected to happen was...:
For llama to stop spitting on me

What actually happened was...:
Llama continued to spit on me

Steps to Reproduce:
1. Kill the wandering trader
2. Sit on the llama until it is tamed
3. Watch as it spits on you even though you became "best friends" as the advancement says