PSoC 4100S device supports up to 1 Mpbs data rate as per datasheet. The issue could be due to timing issues in the I2C bus. Could you please recheck the pull up resistors value used in accordance to the pull up resistor sizing mentioned in the @https://www.nxp.com/docs/en/user-guide/UM10204.pdf .
Rp max = tr /(0.8473 x Cb )
Where tr -> is the Rise time defines in the I2C spec as per speed
Cb is the total bus capacitance.
If this doesn't solve your issue, please share the I2C waveform.