I play with arrow movement keys instead of asdw.
I've noticed when i set any key press to Either Shift or Control, it blocks being able to turn left using the left arrow key whilst being depressed. Forward,down and right are completely unaffected, just Left arrow.
This happens in any vehicle, land,sea or air.
I think it may be some unlisted key bind that shift or control are using that doesn't appear in the option and so cannot be changed.
I have checked all key binds and none clash or interfere with shit,control or left arrow.
It could be the actual keyboard this is a problem. The reason why WASD is the default is because hardware manufactures support it nowadays than what the default used to be 2 decades ago.
This explains why your keyboard could be limiting your key presses because of hardware limitations http://www.microsoft.com/appliedsciences/antighostingexplained.mspx
To combat this as best a possible hardware manufacturers add better support for multiple key presses around the WASD, left-Shift, left-Ctrl, and Space keys. I doubt you'll find a keyboard with better support for multiple presses around the arrow keys
I just tried it out on my game, I didn't have the problem. Have you tried it in other games since this started happening in Arma 3? And can you use that same Ctrl and Shift with other keys?
Ive tried it on other games as i said in my first post. SHIFT seems to be the main culprit, I've recently discovered that right control how ever does not effect the left arrow key, so that's LEFT SHIFT,RIGHT SHIFT & LEFT CONTROL KEY are the problem keys.
I've tested with another keyboard and mouse combo and still the same result.
We could not reproduce this bug.
Please let us know if you are still able to reproduce this issue in latest Development build. Thank you.
Closing due to lack of information / no response in a long time.
If this issue is still reproducable for you, please create a new ticket and make sure to include all necessary info / files.