You may encounter problems with documents being stuck at being queued within Google.com/cloudprint.

The problem arises because Java uses its own certificate store and Cloud Print goes over google.com/cloudprint. Securly proxy Google.com to enforce keyword blocking, auditing, and safe search enforcement as it causes the problem that you are seeing.

To get your Papercut Google Cloud Print working again:

Download the certificate that is attached to this KB article.
Download KeyStore explorer for your applicable Operating System from http://www.keystore-explorer.org/downloads.html
After installing the KeyStore Explorer, please go to File, in the drop-down select 'Open'.
Navigate to the Open KeyStore window for your installation. In my case, it was C:\Program Files\PaperCut NG\runtime\win64\jre\lib\security and select "cacerts" for the KeyStore to open and click "OK".
The password to unlock the keyStore is: changeit
Please click on the red ribbon titled "Import Trusted Certificate".
Select the certificate that was downloaded from this KB article and click "OK".
In the Alias name, please leave this to the default *.securly.com and click on "OK".
Click "OK" on the alert letting you know this was successful.
Please ensure that now at the top you see *.securly.com listed (as shown in the screenshot below) then click on the floppy disk for "Save".
In order for PaperCut, we must restart the services so that it sees the new certificate. Please click on your start button and type in "services" and click the services button (alternatively a reboot of the server will also work if possible).
There are 3 services for PaperCut, starting with "PaperCut Web Printer Server" right-click this and select "Stop" and repeat for the remaining services.
Then, starting with "PaperCut Web Printer Server" right-click this and select "Start" and repeat for the remaining services.

Why is Papercut Google Cloud Print not working with Securly