Sync has never worked correctly

All my available devices do not display on screen when I am in tab share mode. I receive Tab Sent notice when sending, but new tab doesn't show up on other device. When I sync my device it says sync complete, however nothing seems to syncs ever, tabs on browser don't sync with anything, but nothing different on other devices. Open tabs on one device do not migrate to other devices when Firefox browser is opened. New desktop pc does not show up as available device to sync with or send tabs to. All devices are signed in and synced yet nothing really syncs