The first screenshot below shows a trigger that should only fire if the latest 4 values have a string length greater than 0.

The second screenshot shows the last 4 values and it can be seen that only 1 and 4 have strings.

The trigger fired at 11:30, despite the previous value being 0. It cleared when I manually ran the item at 11:41 and it has fired again at 12:15.

It seems that the trigger is only looking at the first value and ignoring the other 3.