Why are computers dropping from my TeamViewer account?

I'm using custom TeamViewer Host that auto assigns itself to my TeamViewer account. Randomly time after time some computers just drop from my account and are shown as "offline" and I cannot connect to them anymore when looking from web management.

When I go and physically check what is happened to my TeamViewer installation it is running and seems to be working normally but when you look at the settings it's not assigned to my account any more. I don't know why this is happening time after time. I'm using TeamViewer version 12 and my hosts are Windows 7 and Windows 10 machines. This is very frustrating.

Any ideas, logs or something where to start solving this one?