Model number of the product(s)?
Problems you were having?
I see here Hardware Trigger with External Signal (Featuring Multiple OV9281 Global Shutter Camera) - Arducam that you use an Arduino Uno to trigger the camera.
The digital output of the Arduino Uno is 5V. And FSIN should be 3.3V (3. External Trigger Camera Application Note - Arducam).
Is it safe to use the Arduino Uno digital output 5V to trigger FSIN?