The TCA9517 datasheet mention the MAX VOL of SDAB is 0.6V. From the picture, we measure the LOW voltage is about 0.76V at the beginning. What reason cause TCA9517 over Spec? That may cause I2C Fail.
The design is from MCU input pull high to 1.8V to TCA9517 output pull high to 3.3V. Pull high resistor is 10k.
Ch1: Clk
Ch2: SDA from MCU
Ch3: SDA output from TCA9517