I think I figured it out! This worked for me at least. First, make sure the contact poster is restored to default. Go to edit > poster > “Aa” under Monogram > color > default grey in the bottom right. It may then ask you if you would like to change the photo to match this, but it doesn’t matter if you do or not (it won’t match either way). Then, for the contact photo/avatar itself, you first need to make sure that the contact photo you want to change is an actual photo, not just a colored monogram. I’d honestly suggest changing the photo to just some random photo in your camera roll just so it’s something fresh (this will be only temporary). If it then asks if you’d like to change your poster, keep it as the default color you just set it back to. Once you’ve set the poster back to default and updated the avatar to some random photo, go to icloud.com and sign into your iCloud account. THIS HAS TO BE ON A COMPUTER WEB BROWSER, IT WILL NOT WORK ON YOUR PHONE’S BROWSER. Find “contacts” and search for the contact you’re trying to change. Click edit, then the minus button by the contact photo, then hit save. This should restore the contact photo on your phone to the default monogram. If it doesn’t fix it right away, try refreshing on your web browser or restarting your phone, but it should change on your phone instantly. Hopefully this works like it did for me!
