Bad macro block when using cavlc encoding

[dvbrain]

When using x264 do intra encoding with tune fastdecode, we found some frames got wrong outputs.

When using command line:

x264 -o x264_test_sample_2.264 --input-fmt raw --input-res 3840x2160 --fps 50 --input-depth 10 --input-csp i422 --output-depth 10 --output-csp i422 --preset ultrafast --tune fastdecode --qp 12 --keyint 1 --slices 8 --no-cabac --threads 1 x264_test_sample_2.yuv

We got this:

When using command line:

x264 -o x264_test_sample_2.264 --input-fmt raw --input-res 3840x2160 --fps 50 --input-depth 10 --input-csp i422 --output-depth 10 --output-csp i422 --preset ultrafast --tune fastdecode --qp 11 --keyint 1 --slices 8 --no-cabac --threads 1 x264_test_sample_2.yuv

We got this:

It seems the first micro block of slice 6 is corrupt encoded. The gray bar will disappear if we modify the Y value of pixel (0, 1344) from 721 to 711.

The source YUV file:
https://drive.google.com/file/d/1Wx3...ew?usp=sharing

Hope somebody can help us to fix this problem.
Thanks.