Go to the BP_SmartAIComponent then go to the Crouch Check function then change the Trace Channels on the nodes shown below to Cover.
NOTE: The following is for if you are using your own player character blueprint.
Go to your player character blueprint, then in the components panel select the CapsuleComponent (Inherited) then in the details panel find the collision section and make sure you setting look like the image below. It should look like the image below.
Next select the Mesh (Inherited) component again this is in your player character blueprint and in the details panel find the collision category then in the Trace Responses section make sure that Cover is set to Ignore. It should look like the image below.
If you custom player character blueprint has other meshes or skeletal meshes you will also want to make sure that they are set to Ignore the Cover trace channel.