Take a look at the picture, when you have the enemy unit at the very top of the screen and the attacking unit just below, left clicking doesn't trigger the attack.
V1.00.08
Monitor res 1680x1050
GG's AWD, GG's WBTS, GG's WitE Beta Tester
Beta Tester: Panzer Corps, Time of Fury, CtGW, DC CB, DC3 Barbarossa, SC WWII WiE, SC WWII WaW, SC WWI
I've experienced the same thing. You need to scroll the screen a bit, the top rows are kind of protected from clicks (at least that is my idea about what might be the reason).
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