Not sure whether this was a bug or not at first, im now pretty sure that it is not working as intended.
The problem is that the path finder give you wrong results regarding whether a path can be found or not. And that the calculations or way It figures out what cell is the best alternative is not working correctly as it ends up selecting invalid cells even though others are valid.
Here is a short example:
Shows the starting position of the unit. And the big green square is a solid.
If the unit is told to move to either the left or top side it will work fine.
But when told to move to right or bottom side it fails.
Doing some testing it seems to indicate that these two sides have some problems, as moving the starting position doesn't have any effect.
Result in the same problem
It seems to be that a target destination to an empty cell near the original target when its a solid is not found correctly and therefore gives you wrong results.
Using the above example where the unit is starting above the big green square, the possible paths to the destination and the best possible path (indicated by the red square) to the target would be like this, so there should be no reason for it to give you a path not found.
Description of Capx
Will just path find to a selected target. chosen by left mouse button.
Steps to Reproduce Bug
Click any of the solid tiles on the right or bottom side.
Will give you the result that no path could be found.
That it finds a path to the best nearest empty tile that it can reach.
Operating System and Service Pack
Construct 2 Version ID
Don't think it have anything to do with this version as I believe this problem have been there for a very long time.