Alright, glad to hear that it’s fixed. 
I saw that you have a floor mesh on which you’ve placed your grid generator. So just set it’s collision settings to block the GlobalAbilityTargeting trace channel, & add the GlobalAbilityTag to it as well. It should start showing the reticule on that surface as well.
In the map shown in the screenshot, I’m just using the Unreal Engine’s nav mesh to calculate the path points. But if you check out the second map focused on the spline based paths, you can see how to create an AI pathing system similar to how it’s done in Kingdom Rush. While you will have to draw out the spline yourself, the toolkit provides you with the support for automatically creating user specified number of multiple spline lanes around the primary lane as well as customization of other parameters like lane gap distance, spline sharpness, etc. You can control all these settings through the Enemy Spawn Point actor:
Also make sure that you set the parameter ‘Navigation Type’ in the Wave Manager actor details to 'FixedSplinePath; as shown below:
This parameter basically informs the AI Bots about the type of pathing system they are supposed to use.