My texts are never fully updated & synced on my Macbook Air.

My Macbook is only about 2 years old and from the first day I got it, it’s never accurately synced my texts 100%. I have icloud on & have even tried selecting “sync now.” They will sync eventually, but they’re always anywhere from a few hrs to a week behind. Just now I opened it up and luckily a new message just came in, but the rest of my threads are still at least a day behind. A while back, I contacted someone from Apple who walked me through fixing this problem, but it only worked temporarily. It’s never been synced perfectly the way my phone and ipad are.