Thrumbo walked away after I tamed it

[ILV]

A14 1238, no mods

Reference image (Korean): http://steamcommunity.com/sharedfiles/filedetails/?id=727383842

I'm new at this game. While I playing, Thrumbo appeared. I wanted to tame it but my colonists weren't enough to do that(one who has the highest taming skill level was only 12). It was my first moment I met this creature and I could load the game if somethings go wrong, so I ordered to tame it. After several days, the last morning thrumbo move out, it's ridiculous but one of my colonists successfully tamed it (like image on the link, with 0.5% chances). I couldn't believe that however, she just kept going and walked away.

I'm so confused and sad.