First of all, check if the AI nodes are actually loaded, type: in the developer's console. The connections should now be displayed as green lines on the floor, just like in the preview picture.

If those lines don't show up (meaning that there are still no AI nodes), you can try:
1) Completely quit gmod, unsubscribe the addon, then subscribe again, and restart gmod.
2) If the nodes are still missing, then you should unsubscribe from the addon, and manually place the .ain fine in the directory:
You can download the .ain file from here: https://github.com/agentOfChaos/Misc-Steam/raw/master/maps/graphs/gm_akb2.ain
Or, you can just clone the git repo, if you prefer.