Wandering trader's arms have rendering issues

The hands of the wandering trades don't appear always as they are supposed to be

Steps to Reproduce:

1. Summon a wondering trader
2. Move around him and observe
3. Hold an emerald and move around him again

Observed Results:
His hands might dissapear both when you hold the emerald and not.

Expected Results:
His hands should be always crossed on his chest and never desapear

Screenshots/Videos attached: Yes