QuickBooks Integration isn't working

I connected my QuickBooks account to Toggl and it said everything went through okay, I chose the account I wanted to integrate with in QuickBooks and hit connect. It succeeded and now it claims that it is connected:

However, when I go to Invoices and hit “send to QuickBooks”, the screen just goes blank. I looked in the dev console and saw some JavaScript errors.

In Invoices, I looked in the Network tab in the dev console in Toggl and there is a network request spamming GET requests to https://track.toggl.com/integrations/api/v2/services/1394348/quickbooks/customers. Over 2K requests while I wrote this.