Quote Originally Posted by spcw1234 View Post
Nothing specific to that pin that should cause an issue. Have you measured voltage at that pin? It sounds like it is floating, possibly due to a broken trace or a bad connection.
When measuring the voltage at the pin with the LED illuminated the presence of the meter causes the input to behave as expected and the voltage is around 300-400mv. With the LED off the voltage is ~5.4V. I have three boards that are all exhibiting the same problem so don't think it is broken trace or bad connection.