VMWare Host status Gray after update to 2.2.10

Hi,

we have just updated our Zabbix installation from 2.2.9 to 2.2.10. After that 10 ramdom ESX 5.1 and 6.0 hosts suddenly show their status as Gray. Nothing to find in the VCenter, though, all is OK as it was before the update.
Tried to delete the hosts and also one of the VCenter servers but the same hosts reappear in Gray.

Server Parameters changed from Default:

StartVMwareCollectors=4
VMwareCacheSize=256M
VMwareTimeout=30

Template is a modified Template Virt VMware without "Discover VMware VMs" discorvery item as we do not need that.