Using "Template VMware VM" against vCenter 6.5

[ChrisP]

Are there any special settings I need to implement on my vCenter 6.5 appliance to get it to work with Zabbix 3.4.11? I am getting "Unknown VMware service error" when using the "Template VMware VM" to collect data in the "Latest data" report. The VMs running within the vCenter are being discovered and added in Configuration -> Hosts labeled as "Discover VMware VMs:".

I have enabled VMware monitoring in /etc/zabbix/zabbix_server.conf

StartVMwareCollectors=15
VMwareCacheSize=2048M
VMwareFrequency=60
VMwarePerfFrequency=60
VMwareTimeout=10
CacheSize=4096M

Anyone have a suggestion?