Thanks for providing your ESS account email. This let me check the logs quickly and I saw there was never a Push to ESS done. It’s a critical step to avoid the sort of “incomplete” syncing you are experiencing.
To quote the ESS guide here on forum:
Important: now you need to click the Push button to ensure all existing items and tags from that device get added to ESS. Otherwise syncing may be incomplete, resulting in missing tags, projects and so on.
Please try doing a Push from one of the devices with complete data, and it will most likely fix the problem in your case.
A similar issue was was also described in this topic: [Fixed] Tags not sticking (and erasing themselves) on Android app with ESS enabled - #6 by Andrei
@bpeter I don’t know if this fix applies to you without knowing the ESS user id. But it won’t hurt to try as it’s often the case.