STM32 HAL I2C and MLX90621
According to I2C specifications, when so-called "combined format" is used,



there should be "repeated START" in between configuration stage (internal start and stop addresses, and the number of bytes to read) and READ function, but no STOP.

When the interface encounters STOP, it "forgets" the submitted read parameters, so the next stand-alone READ doesn't know where to read from, and NAKs.