Cannot send photos in a Messages from my MacBook - but can from iPhone and iPad

MacBook Pro 2020, MacOS 15.6.1 (24G90)

Hello all - I can send photos in texts from my iPhone 13 and iPad Air 5th Gen. But when I try to send photos in texts from my MacBook they don't appear to the recipients. They'll get a gray square or an empty blue text bubble. Same holds true if I send a photo from my MacBook to my iPhone or iPad.

All three devices are using the same Apple ID, "enable messages in iCloud" is checked on. I have synced iCloud. This happens whether or not I use "send low resolution" option.

Does anyone have experience or guidance they can share? Thanks.