If anyone still sees the issue, please post a test case that we can run here with the latest Firefox and UI.Vision version. We can only fix bugs that we can recreate.
You can also contact us directly at team AT ui.vision and we can give you access to our test system (e. g. Windows 10 + Firefox 71 or Ubuntu plus Firefox 71) via RDP, Teamviewer or Anydesk, so you can directly recreate the issue on one of our test systems.