Why Queue is starting

This can happen from few different things:

1. If you are using an Target base model, you need to check that you didn’t pass your target capacity, you can check this in your server setting. 

2. If you are using a FIX IP the number of parallel scans is limited to the server capacity, this will allow 4-5 scans to work at the same time.
3. When scanning more than one asset you need to check how many engines you have in your package you can check it in the server info under concurrent scans 
4. Using a Proxy (the same one) always limits the number of scans to 2, you can’t pass this limit.