setActionThread doesn't play certain animations

I've spawnSphere where I spawn BoomBot model as AIPlayer instance, in attached script I've only one string:

$gTestNPC = $SpawnObject;

(btw how can I get model in world by name? It certainly not suitable to have bunch of global vars per NPC)

Then in console I do

$gTestNPC.setActionThread("head");
$gTestNPC.setActionThread("side");

Where "head" does work and "side" doesn't. What can cause such behaviour? Both animation seqence are present and playable via shape editor.