MacBook Pro not appearing in Find My despite being signed into iCloud

I've had and used an Apple/iCloud account for years, with many devices and items (e.g. AirTags) and family members. FindMy has always worked seamlessly and easily with everything. The MacBook Pro M4 Pro I purchased last November, however, is another story. (Pretty sure I used Migration Assistant, which I suspect may be the root cause.) Honestly I believe FindMy worked at one time, but recently I noticed it is not working. I've disabled and re-enabled FindMy, logged out and back into iCloud (under either my email OR my phone number), restarted and done complete shut downs of my computer, done a SafeMode restart, even enabled Home since some have found that helped. And absolutely nothing works; I've even had dialog boxes stating a new device was added to my iCloud account (and 3-month trials for Arcade and Music re-activate), but the MBPro is not in FindMy. Also I can be on the laptop in the FindMy app and it sees every other device and item except itself, and other devices (e.g., iPhone 15) see themselves and all devices except the MBPro. Pretty much at my wits' end.

[Re-Titled by Moderator]

Original Title: macbook pro findmy not working