Hopefully I can shed a little light on this topic. The AIN4-20mA unit uses a STM32 processor to handle the I2C interface in software. For some reason, the timing is not wholly compatible with the Raspberry Pi kernel I2C drivers. However, the Espressif I2C implementation is a lot more tolerant and flexible and works just fine. That's why it works with the M5 controllers. There was a an update to the github repo for this unit's firmware (https://github.com/m5stack/M5Module-4-20mA-Internal-FW) which changed the I2C library that was used. It's possible that this will fix it, but I haven't bothered to set up a STM32 development system to try it. If you really want to use a Pi or other Linux host board, you could use any inexpensive ESP device (like an M5Stamp) as a go-between. Another option is to use something like the Arduino UNO Q, which runs Linux on the main processor and allows you to run C++ code on the STM32 microcontroller to talk to I2C devices. It's really better to run real-time control on a separate microcontroller anyway.