First make sure that your Lansweeper service is running. In the Service Status box of the web console landing page, do you see a "Service Stopped" message? If so, please try restarting your Lansweeper service.
Your scanning queue can be accessed by clicking the name of your scanning server in the Service Status box. In the example attached to this post, the scanning server is called "Lan-001". Your scanning queue shows you the scans that are currently being performed.
Within your web console landing page you will also see a "Last scanned" section. What is the "Last seen" date of the top computer in the list?