I changed to the dev branch and the fine stance adjustment issue was solved for me.

Apologies in advance, I don't really know what I'm doing.

I could not find any reference to fine stance adjustments in my controls settings despite picking through every category with a fine-toothed comb. I wondered if the settings for my existing profile were corrupted, so I tried to create a new profile, only to have the same issue. I searched within the text file for my profile (the text file found in C:\Users\mywindowsusername\Documents\Arma 3 - Other Profiles\myarmaprofilename\myarmaprofilename.arma3profile) and found no content related to keybindings, despite that a friend of mine located his keybinding information in his own version of that same file.

My friend sent me his list of keybindings and I added that to my profile file and found that stance adjustments work for me after doing so.

To be more clear, here were the contents of that text file as I found it:

http://pastebin.com/wk81aJYs

Here is what I added to the file, as supplied by the friend: http://pastebin.com/Aq2FsDja

This has solved the issue for me for the time being.