camera switching

[Quez]

I use 2 Tenveo USB conference cameras on a usb hub connected to a laptop. at a monthly meeting, to connect those who cannot attend in person to the meeting.  One camera is used for the committee and the other and the other for our visiting speaker. The laptop also carries audio from the sound desk and connects through a wired network in the building. This laptop is also connected via HDMI to a projector in the hall. It does nothing else and is not the host. It is logged in as a participant called camera control. This is normally spotlighted  so that it is the main picture going out to zoom and  is also put up on screen in the hall, whichever camera we have switched We start the meeting on Camera 1 (committee business) then switch to Camera 2 when the speaker has been introduced at the end of the speakers presentation we switch back to Cmaera 1  for the committee again. Up until 2 months agio this worked well.  At the last 2 meetings I found that switching back to camera 1 after we had switched to Camera 2 gives a black screen  (it appears to be connected ) and we have to disconnect that camera and reconnect to get it back. Using Windows 10  no changes made to the system I would be grateful if anyone has any ideas as to how we can get back to it working again 

Regards

Frank

P.S.  tried switching cameras via drop down box and using control + n makes no difference

[ExpertswhoJohn]

Zoom can change the audio and video source, but it is the Windows System that detects and manages the devices. Almost always, the problem is within Windows.  When you plug in a new device, Zoom will try and make it as the live source when not active.
it sounds as if Windows is not initiating properly.
I find that his issue becomes one of the USB or HDMI cables. There is a wide variety of quality of the cables and a poor signal cable may not give the correct voltage for the USB device to be set up. This will spot windows, and hence zoom will be unable.
So please try new cables and possibly a difference connector.