Defender for Endpoint API vs Website

I use the Defender for Endpoint API to tag some devices. This generally works fine.

 

Now I have the following situation for some days now (so no "sync" problem)

 

On the Website I have a specific dns name (device name) which appears two times on the website, but I only get it one time via the API.

 

What I did with the API:

•  Try to get the device with the guid provided in the web. One guid returns the object, the other returns 404-Not found
  
  Call: https://api.securitycenter.microsoft.com/api/machines/<guid>
• Read all Machines and try to find the dns / the guid - did not find the missing device. 
  Call: https://api.securitycenter.microsoft.com/api/machines

As far as I know, you cannot restrict the permissions for the devices in API queries.

 

1. Why they are missing?
2. How can I get the "lost" device?
3. Anybody with the same experience?

Any ideas? 

 

EDIT: This device is even not consistent in the web view. If you add a tag and filter after that tag, the device does not appear.

EDIT2: This device can be found with the API, if you add a tag and get all devices of this tag. But still is not in the list of all devices and cannot be call by the device guid.