If the hub has been taken apart, it's possible that the locknuts were installed on the wrong side, as both locknuts are not the same.The non-drive side (NDS) locknut has a larger diameter (by ~0.031") and a deeper bevel. The TL-FW30 will not fit over it. If your tool fits over the locknut currently installed on the non-drive side, then the locknuts have been switched, side for side.
Edit: The non-drive side locknut dfoes not fit into either of my two Shimano TL-FW30 or my Park tool. It's a light interference fit with mu LIfu.
