I considered posting this in the Virtualization Manager forum, but I think this is an NPM issue. I occasionally have VMs that alert due to high memory, but the issue is really that Orion is putting the wrong values in the database. Let me explain with a picture:

As you can see in the left-hand column, the highlighted part shows 'Memory usage of this guest', which is supposed to be a percentage. It is instead showing the actual value of the memory being used, rather than a percentage, which you can see in the right-hand column. The corresponding VM in VMAN shows '50%' usage everywhere, too.
Is this a reported bug or has anyone else seen this before?