Hi @mbarney I have come across the I2C issue, and trying to remember what I did, or solution. There was an update that could fix it, but of course that is a fork.
It might have been that a wrongly soldered I2C for a humidity device caused the problem for me. Arduino paradigm is typically normal use cases.
The Mayfly 0.5b has pullups R8 & 10 of 2K. The ADS1115 board has its own pulls up of 10K.
The ADS1115 digital inputs are specified for 0-5.5V, which I think means they won’t take any current when turned off V=0. However the boards pull down Rs would likely interfere with the operation of the pull ups R8&10
So I wonder if desoldering the ADS115 boards I2C pull-ups would make a difference. Just a thought.
I recently used an LTC2942 directly connected on the Mayfly I2C no pullups, it is similarly specified on inputs 0-6V. I had no problem communicating on the I2C.