Grove OLED Feather issue

My units were working fine but then today (after being off all weekend) my Argon is not communicating with my OLED display. Both units are in a Grove feather shield. Can you think of any reason why this would stop working?

Too little info to advise.
What state is the device in?
What does the RGB LED do?
Do you have any USB Serial output that may help debugging? If not, add some.

Breathing Cyan, outputting to the console temp and humidity from DHT11 just llike it was the other day when it worked. Everything is working except the Grove 128x32 OLED.
Two different Argons have the same issue (I have 2 argons, 1 OLED, tried it on both). The reset button on the OLED feather works.

Update. The I2C scanner can see the unit.

Have you double checked whether the address reported by the scanner matches the address used in your code?

And for the sake of locating possible causes I’d reiterate