I had an issue after a inplace upgrade of a Hyper-v 2012R2 standard to 2016 Standard. ALl VMs is missing and there is no errors in the eventlogg.. Running the below command fixed the issues and all vms reappeared in the MMC. Havent had the time to real figureout what it does, beyond that it has to do with WMI settings that gone corrupt.
"The Managed Object Format (MOF) compiler parses a file containing MOF statements and adds the classes and class instances defined in the fileto the WMI repository. MOF files are usually automatically compiled during the installation of the systems with which they are provided, but you can also compile MOF files by using this tool. "
