SMS messages not syncing between MacBook Pro and iPhone

Ever since the Big Sur launch in 2020, my Messages app on my MacBook has been glitching. Notably, SMS messages will appear as “unread” for days and weeks at a time on my MacBook although I’m actively reading and replying to them on my iPhone.

Additionally, my Name & Photo Sharing feature does not sync between the two. I’ve been dealing with it for months and have tried all retail solutions, to no avail.

Has anybody else experienced / solved this?