Cannot send Message - MMS needs to be enabled to send this message

I receive this notice when I try to send a message with an attachment from my MacBook Air (15", M2, 2023, running Sonoma 14.4.1), although I am able to do so from my my iPhone 14 Pro (iOS 17.4.1). Both devices are connected to my iCloud account, so this should be seamless, and was for years until recent Apple updates to both operating systems.

From reading earlier posts on this problem, I have tried going to Settings -> Messages and turning iMessage off and then back on, then clicking on "Send and Receive" to be sure I can send and receive messages from both my cell phone number and my Apple ID. No option of "Text Message Forwarding" appears on my iPhone to allow forwarding from my iPhone to my MacBook Air.

Thanks in advance for any ideas.