So I was asking in the shoutbox about it as I couldn't seem to reach the location where it's located (as is instructed on bbb) from neither that first floor map nor from lab area b1 and somebody mentioned that there was a source update that said it did spawn at it's location (so that much might be true but I stil can't reach there). New Source Update #34 07/07/2017 Maps: Chimera will now spawn at Lab - Secret Basement Path. So I'm not sure if this is a bug or not but I thought I'd report anyway.
