WAN Quality - Interpreting RRD Chart/Packet Loss

[BNaCl]

I am a bit confused by what I am seeing on the Reporting > Health > Quality > WAN. Specifically I am seeing intermittent loss represented as 100m or as high as 500m. I am expecting a percentage, so what does the "m" stand for? Even more confusing, I can find no other metric to corroborate the loss being reported. CPU/RAM and WAN bandwidth is not under strain (at all) and I cannot reproduce any ICMP packet loss via a manual ping to line up with what the Quality chart is showing. Internet quality tests (DSLReports, Ookla) come back clean and I also have moved the "monitor IP" to other reliable IP's and get the same result.

Thanks in advance.