XenServer 7, Ubuntu 16.04 - what is the problem with guest-tools and how to fix it?

Question

ubuntu

There is XenServer 7, it has (for example) 2 virtual machines with Ubuntu Server 16.04 LTS.
For one virtual machine, XenCenter shows the following virtualization state:

This system was obtained from 14.04 by do-release-upgrade. While it was 14.04 the same thing was shown. It was also installed on XenServer 6.5, then it was migrated to 7. When it was installed on 6.5, everything was displayed normally.
But this system was installed clean right away on XenServer 7:

On the first system, after do-release-upgrade, the guest-tools installation command was run again just in case. Nothing suspicious was said.
Question: how to fix it?