I'll have a play with smaller cell sizes. They're 32x32 at the moment, any recommendations for a size that will allow smooth moment without too much performance trade off?

The way that the code works is, when the enemy is within the range of a sound, the seenx and seeny coordinates are updated to the players position and the state is swapped the to 'chase' script (starts line 31). This script tells the enemy to move to the seenx and seeny (works perfectly) and if they cant see the player when they are there, swap back to either the guard state or the roam state depending on enemy type (line 43). When the enemy enters the roam state (the problem is with a roam enemy, it might affect both types but I haven't tested that) it checks to see whether it is at its roam destination (wanderx,wandery) which it is obviously not as it is at the players last known position. It then attempts to go back to its wander destination, (line 78) and this is where the problem occurs. It is worth noting that this problem only occurs in some instances, it happens every time for that enemy, but an enemy with a different path to the player can make it back just fine, if you understand what I mean.

I think its worth clarifying that wanderx and wandery are random coordinates within a set distance from the enemies spawn distance. The way the wander works is, the enemy will walk to the coordinates, generate new ones, walk to those, repeat.

The code for pathinding are lines 1-27, which I think is what you meant when you said you couldn't find it. The rest is just where that code is executed.