Do not decrypt profile not working correctly?

I've got an Toon Thermostat, that creates an openVPN connection to the eneco datacenter for transmitting the usage data, as soon as i enable the SSL/TLS inspection the display shows "no connection to service center. I've created an rule that says "dont decrypt" for that specific host and even the complete network but still it fails on connecting, i guess this problem will occure for more iot devices when the SSL/TLS engine is turned on. When it doesnt connect there is nothing visible in the SSL/TLS inspection logviewe except from "do not decrypt"