Either the Cursor is not on the point of the needle, or the End of Turn button hitbox is larger than it should be, as it is possible to have the point of the needle on the lower section of the Discard and yet the End of Turn is highlighted.

It may be that the cursor is misaligned, as a bit before I thought I had clicked on an easy mission, yet got sent to a hard mission (also, why is it that there is no warning or confirmation that you're going to a mission with no retreat? Even just having the option to retreat on just the first node would have been fine).