Configuration:
DC voltage into A8
Starting voltage: 0V incrementing in 1.5mV steps.

Between approximately 0.2049V and 0.2197V the ADC reading is 4054 (16 bit resolution) or 252 (12 bit resolution)

The chart above shows the very strange behaviour. Notice the other discontinuities above and below. Sorry for the very poor annotations!

Board firmware version: 4.2.4

Any thought on am mbed interim workaround?

Many thanks