Can't send iMessage Attachments to Android users

Since upgrading to Big Sur (11.0.1), I have lost the ability to send screenshots, photos, or any other such attachment to someone using an Android device. I can send text (green SMS) to an Android device, either individually, or to a group of people who are using a mix of iPhone and Android devices. My employees have a mix of iPhones and Android, and for years I have been sending screenshots to my management group from customer reviews, etc. without problem. But no longer and it is really impeding my ability to communicate effectively. From my iPhone 11Pro (iOS 14.2), I can send screenshots/photos to the same group of people, and I am logged in with the same Apple ID on all of my devices. So this is definitely a MacBook Big Sur problem. Here is how my iMessage Preferences are setup on my MacBook: Enable Messages in iCloud is checked, My phone number, Gmail and iCloud addresses are checked, Send Read Receipts is unchecked, and I start new conversations from my phone number. Should I be starting new conversations from my gmail address instead? Has this become a requirement for sending screenshots/photos or anything other than a plain text to Android devices?