Hi,
By default the timeout is 1 second:
static const uint64_t ACQUIRE_FRAME_TIMEOUT = 1000000000;
Please extend it to 5 seconds for a try. Probably the default value is not enough in certain multi-camera case. The source code of nvarguscamerasrc is in
https://developer.nvidia.com/embedded/l4t/r32_release_v5.1/r32_release_v5.1/sources/t186/public_sources.tbz2
Please download it to rebuild/replace
/usr/lib/aarch64-linux-gnu/gstreamer-1.0/libgstnvarguscamerasrc.so