Jetson Nano Gstreamer OpenCV stuck at NvMMLiteBlockCreate : Block : BlockType = 261

Hi,
A user has shared a sample that seem to be close to your use-case. Please take a look at:
Nvidia-desktop kernel: [407343.357549] (NULL device *): nvhost_channelctl: invalid cmd 0x80685600 - #18 by DawnMaples

It creates 16 threads and you can change to single source for a try.