There can be a pop-up in the device after starting erasure that has to do with "Verify apps" feature in newer Android versions. The pop-up typically says: "Allow Google to regularly check device activity for security problems, and prevent or warn about potential harm."
See more information in Android documentation: https://support.google.com/accounts/answer/2812853?hl=en
This pop-up should be acknowledged by the user for the erasure to proceed.