Can you please put in an issue on github with information like the version you are using (there is a hexadecimal hash in the application window title bar) and the model of computer you are using.
You can also retrieve some debugging output. In the 'Set Logging' menu, select VideoReceiverLog and VideoManagerLog, then restart the application and go back to the console tab to see if there is anything of interest.
Any other observations are helpful, too. Does the issue affect recorded video? What is the most recent version you have tried that does not have this issue?