I hate to say this but it seems that i2c read has gotten more unstable again.
Try this at a reasonable speed (Metro or not):
X ADD 1 MOD X 64
CY.POS 1 X
CY.POS 2 CY.POS 1
Apart from the known range read/write bug spot cycle 2 for a while. It is skipping values here every now and then…