Raspi3B ( 3 pcs tested ).
When system boot and CPU throttled ( 0x50005 – always when powered over usb) all OK, video is coming to raspivid.
When system powered by stable 5V and over GPIO – CPU not throttled ( 0x0 ) – PICapture board loose Pi cam port. And not init after soft reboot.
May be system start more quicly – and PIcapture board can not get in time.
PIvideo can connect to board – but pi cam port not active. Any modprobe restart not help.
Cables , quality power source checked by oscilloscope. This bug come on native raspbian build and custom too.
If you can communicate to the PiCapture board using PiVideo then it is very likely that it is not the problem.
We have found that the Raspberry Pi GPU is very sensitive to power conditions when power is first applied and it is initializing. When this happens, the ARM processor can be running properly but some GPU functions including the camera interface aren’t working.
The best suggestion I have is to check the power supply, and perhaps try another power source. The most important thing is that there is no voltage drop at initial power-on when the demand is high.
I power from 10A bec with 4700 +1000 +1000 uF low ESR capacitor direct solder on raspi board, lenght of 18AWG wires 20 mm. I check power sequence with 1000MHz band pass Textronix, I can measure processes less than 1 nanoSec. No power problem.
Pi cam port crashed in moment of starting capture – Red led on Picapture short pulse in moment start Raspivid.
If power from weak 500mA USB source all work good – but throttled bad.
If there is a power sequencing or similar issue on startup, the RPi GPU may not detect the PiCapture board as the camera. This will not be evident until you try to do a capture. At that point, since there is no camera detected, an error will result. Note that once this error occurs it requires a complete power cycle to correct it because the GPU error recovery doesn’t work properly.
I suggest that you remove the extra capacitance you have added and try a standard RPi 2.5A power supply. Note that standard RPi power supplies are 5.3V – 5.5V and are current limited.