I've just run some more tests on a variation of docking distances and large walls for different culture types. As the tests reveal (and as recently pointed out), some wall sections are in fact still bugged, and the units may still refuse to climb up the tower.

However, it appears that a fewer number of wall sections are bugged than there were previously before the docking distances were modified. Either that or all this testing (and working on my project at the same time) has made be a bit

I'm sure that the problem must be related to the coding of either the siege tower or the wall sections. I'd heard originally that there were incorrect coding for certain sections on these large stone walls. If that's the case, then I'd be surprised if any workaround would be relevant to fixing this problem. The code / model etc would need to be redone to sort out the issues with certain wall sections. If only I had the software available to see what was causing the problem...

Jambo, what I've done to test out this bugged area is to go into custom battles. Then select a pre-defined settlement (EG Londinium). The gametype should now snap to Siege Assault in the top-left corner. Simply open the advanced options, and set-up a siege against whatever culture's large stone walls.