Glad you found the source of the problem.
However, I am curious about the USB channels used with each camera. Are both cameras USB-2 or is the higher res camera a USB-3. Perhaps there is a data transmission bottleneck. Please confirm whether their USB level, and whether they share a common USB stream to the PC. Also, if your PC has a USB-3 port, ALL of the attached accessories sharing a USB-3 hub, and USB-3 the PC host port, would work much better with far less data contention on such a link, especially if there is a mix of USB-2 and USB-3 devices in that loop. That’s because a USB-3 camera wouldn’t have to wait for the common port to the PC to become free of any “concurrent” or pending USB-2 traffic, since USB-3 channels are “bi-directional”, unlike two-way alternate USB-2 hogging the common line. Its also the same reason that Ethernet connections are faster than WiFi.
In the long term - even if you have mostly USB-2 accessories sharing a hub – assuming you don’t have the camera on its own dedicated USB-2 channel – it would be wise to change any USB-2 loop to a USB-3 which does a far better job of coexisting with slower accessories.
USB-3 speed owes a lot to its ability to timeshare the data line to the PC.