Issue with Cockpit Transpose all of the sudden

[dresoccer4]

i just got the Corsair and did the first training mission while assigning all my favorite key shortcuts. One of them is using mouse button 2 to transpose the camera around the cockpit (it's like this for every plane). This worked fine in first training mission.

However I just fired up DCS a second time today in order to continue the 2nd training mission. Now all of the sudden the transpose key does not work. I looked in the settings and there's a red mark on it. I tried deleting and reassigning but no joy. I tried assigning multiple keyboard keys but none of them worked.

Anyone know how to fix this issue??