Step 1-Go to contacts
Step 2- Now, there is an option filter click on it.
Step 3- This is the way how you can filter people by.
Step 4- The next step you do is click on campaign and choose Not in any campaign.
Step 5- Then there is an option Not having any incomplete task, click on yes.
Step 6- After clicking on Not having any incomplete task then click on filter option.
Step 7- Then you can see the result. So, this is the way you can check your leads with no tasks.