I lost because my opponent Paralel Universe'd my Chimera, and beat me because of it. It's supposed to do "nothing". Lies.
Read the text directly above that line about PUing a Chimera. It states that only one Chimera may exist on your field at a time. The description of PUing a Chimera is incomplete; it has the effect of doing nothing if
you PU
your own Chimera. This happens because you can only have 1 Chimera on your side of the field at any given time, so the new one would simply absorb the one you had already played.
Now if the opponent PUs the Chimera then something would be able to happen unless they had a Chimera already placed on the field because the rule is that only 1 Chimera may exist on a player's side of the field at the same time.
I do understand the confusion around the description of PU + Chimera, but it has nothing to do with a bug in the game; the description of how it works in the very first post was just missing a bit of information.