The user may have a firewall blocking their connection. Please have them check their JavaScript console (instructions for how to do this can be found at the top of this page) to see if any requests are being blocked.
Some aggressive privacy and adblock extensions have been known to block our application due to our use of standard metrics tracking, such as Google Analytics. To check if this is the issue please have the user check their JavaScript console (instructions for how to do this can be found at the top of this page) to see if any requests are being blocked.
Some antivirus software is known to cause issues with the service. Before submitting a ticket, please ensure that the issue can be reproduced without all antivirus software disabled.