Mac "Control" key not triggering PC "Ctrl" key

[ARAURA]

All keyboard and mouse controls are working perfectly fine, but there does seem to be a key that triggers the "Ctrl" key for a PC game, not even the "Control" key on the Mac keyboard.

The game I'm playing is Space Engineers over In-Home Streaming from my local PC to my Macbook Pro. The streaming is working just perfectly, this is the first time using it since my router was upgraded and there is plenty of bandwidth for a seamless and high quality stream. It's just the "Control"-"Ctrl" key that isn't working.