@Wouter_D 

Hi,
You can try to uninstall the 'ip camera viewer' app on your PC, reinstall it, remove the camera from the 'ip camera viewer' app and re-add it, then check if the camera will display properly on the 'ip camera viewer' app and our Tapo app.
Best Regards

  @Wouter_D 

Hi, 
Do you have the same issue when watching the camera on your PC with iSpy or VLC app?
Can you send us a video showing the reported issue?

You can upload the video to your cloud server(such as Google Drive), generate a link to download it and send me(@Solla-topee) the link via a private message.

Best Regards

  @Wouter_D 

Hi, 
Do you mean you failed to establish the Onvif connection with a third-party app after upgrading the firmware? If so, you can refer to the instructions below to troubleshoot.
What can I do if fail to stream the Tapo camera via the RTSP/ONVIF protocol?
 

If the problem remains, please confirm:
  1. Please list the troubleshooting you did and the results.
  2. What's the third-party app?
  3. Please describe your network diagram in detail. 
  4. Can you control the Tapo camera locally and remotely with the Tapo app?

Best Regards

  @Wouter_D 

Hi,
It's hard to say if the problem is on the camera since the camera works with Tapo app and other third-party apps/programs. 
  1) Do you stream the camera on the Tapo app, NAS, security eye, and IP Camera viewer simultaneously? If so, disconnect the connections between the camera and NAS & security eye for a try.
  2) What's the version of the IP Camera viewer?  What's the OS version of your PC installed with the IP Camera viewer?
  3) If you do not pan or tilt the camera on the IP Camera viewer, can you stream the camera live feed normally?
Best Regards

  @Wouter_D 

Hi,

I have escalated your case to our tech team, and they will contact you via email to further assist you. Please wait patiently.

Best Regards