Good news, a major firmware update (2.0) is apparently coming this month! Hopefully that fixes up some of the issues you're having. It's apparently adding tethering as well if you're into that. But before you bench the camera while waiting, make sure you are familiar with the following 3 settings which can cause erratic behavior with exposure compensation:
1) Auto ISO (iso button on top of camera): This needs to be on for the exposure compensation to work. Also make sure the range is not too narrow since the camera won't go outside this.
Example: it's a really bright day and the auto-iso sets iso160. You are currently at -1 compensation, but no matter how much you turn the dial it won't lower the exposure since the camera is at the minimum possible iso already.
This quickly becomes confusing because it seems that there is a difference between the current exposure and the setpoint exposure. What you see on screen is the current exposure, in other words the exposure the camera is currently using based on your settings. When you turn the dial you are changing the setpoint exposure, in other words the exposure the camera is trying to reach (but may not be able to). Since this setpoint has no on-screen indicator, it can look like turning the dial isn't doing anything when you are far outside the range of possible iso values.
Example: on the same sunny day as above where you are stuck at -1 compensation, if you keep trying to lower the exposure, your setpoint may go all the way down to -5, but the on-screen indicator will still show -1 since the camera can't go any lower with current settings. If you start to turn the dial in the other direction to increase the exposure again, it will look like nothing is happening! This is because you have to move your setpoint all the way back up to above -1 before the on screen indicator will move, and this may take quite a few clicks of the wheel since you are down at -5.
Recommendation: Set iso to auto with as wide of a range as possible. Be cognizant of very bright or very dark scenes where your exposure settings may be out of the range achievable by the auto-iso, as the exposure dial will seem unresponsive here.
Tip: half press the shutter to check your current iso, if its 12800 (max), or 640/320/160 (min depending on DR settings), then the exposure compensation dial may lose responsiveness as you are at the limits of the camera.
2) Dynamic Range (Settings->IQ->page 2). DR100 is normal, at this setting the camera's minimum iso is 160. DR200 lowers the exposure of the bright areas by 1 stop, but increases minimum iso to 320. DR400 lowers the exposure of the bright areas by 2 stops, but increases minimum iso to 640.
We just saw in the Auto ISO section above that having too small an ISO range can make the exposure compensation dial seem unresponsive. Activating the DR200 or DR400 settings further shrinks this range, making it seem unresponsive over an even larger range of settings. Using the "auto" DR setting is even worse, since the camera will be trying to change the DR to what it thinks it should be, which may directly counter your manual exposure settings! You are then in a fight with the camera over exposure which makes the exposure meter jump around erratically.
Example: In our example above, our exposure compensation was unresponsive at -1 and lower. If we now turn the camera to DR400 it may be unresponsive at +1 or lower.
Recommendation: Set Dynamic Range to DR100 (at least when you don't need the higher modes)
3) D Range Priority (Settings->IQ->page 2): This combines the dynamic range settings with alterations to the tone curve. So the same issues that exist with the DR settings (higher minimum iso, problems with the camera fighting against your manual settings) will occur here as well.
Recommendation: Set D Range Priority to off