I had a previous SolarWinds case in for this but I'm afraid I no longer have access to it's case number anymore... There is a problem/perspective issue with the new ASR platform and how it reports memory since it is running on Linux. When it reads memory there are two ways to look at it -- the whole platform memory or the IOS daemon memory (if I recall right). To monitor the memory I wanted (what was actually available in the IOS [routing table, etc]) , SolarWinds provided me a special application that would look up a node's MIB table and allowed me to select which OID I wanted to poll for memory usage. This allowed me to select the other OID and it would report the other memory perspective giving me what I felt was the more appropriate/significant memory usage... A quick note on this app, the node's OID custom setting would occasionally get reset back, I believe when I updated my install or some other case when it re-read the polling points for the node.
If you ask Cisco, this is by design... I don't know if SolarWinds was going to change how they handled ASR memory reporting but I assume it's being handled 'by default' the way all other platforms are. Which in this case, isn't quite accurate for what you probably want.
