Troubleshooting for the software can be hard since the official website doesn't provide anything about it. I've checked every part of the website and nothing. No document, download or something to use to diagnose this issue.
The only thing found was an email that you can use to get in touch with the developers: firstname.lastname@example.org
Additionally, you could try reinstalling both the software and the browser. In the browser, press CTRL + SHIFT + Delete and check all the options there except passwords.