As a follow-up, I got I2C working through specifically addressing the chip as specified in the docs, but i2cdetect never, even now, returned accurate information. i2cdetect response such as this (30-37, 50-5f) useless for troubleshooting; does not indicate anything about state of i2c bus.
Thanks to the OP for downvoting my last comment, I hope you downvote this one as well.