I'm also seeing tab sync issues.
My Mac and my iPad both show my iPhone twice, and neither listing has an accurate list of current tabs.
Group tab syncing is also wonky. If I create a Tab Group and add a tab to it on e.g., my iPad, the new tab doesn't always show in the same tab group on my other devices. The Group seems to sync successfully between iPhone and Mac fairly reliably, but it's been about ten minutes and a tab added on my iPad still isn't appearing on my Mac nor my iPhone.
Cross-device syncing is enabled via the in-app settings on each device, and Orion is checked in the iCloud system settings on each device. I have quit and relaunched Orion on each device and restarted each device since I started seeing these problems.