I have experienced with a number of characters that when I start my turn, and I click on the target that I want to melee attack (the worg in the first goblin battle at the gates in this case). As my character runs up to attack the worg the worg gets an opportunity attack on me and my action is wasted, no melee attack done to the worg. The log said that all that happened was that the worg opportunity attacked. No mention of my main hand attack yet the action was spent?