When it is block, I am sure that the camera sensor is normal in the oscilloscope.
Please check whether there are any commit buffer failure.
If the host is streaming data at slower rate, there may be a buffer over flow.
Please refer the following workaround for commit buffer failure error: Invalid Sequence Error in Multi-Channel Commit Buffer - KBA218830
Please probe HSYNC, VSYNC and PCLK and check whether there are as expected.