When I look at, say, Nightly 37 and the CYCLE_COLLECTOR telemetry, the only line shown in the section "histogram evolution" is submissions. Likewise in the "Date range selector". The histogram section at the bottom look fine to me. I looked at Aurora and various other measurement things and they also seemed broken. Some didn't even show the submissions line. http://telemetry.mozilla.org/#filter=nightly%2F37%2FCYCLE_COLLECTOR&aggregates=Submissions&evoOver=Builds&locked=true&sanitize=true&renderhistogram=Graph
mreid and I looked into this a bit. It seems like the problem is that the default now is to only show the series for "submissions". If I click on the box under "add series" and select them all, it works. This also happened to me when I looked at it in Chrome, and I'm pretty sure I haven't looked at telemetry there before.
In a new Firefox profile, going to telemetry.mozilla.org, it shows just the submissions line.
Anthony Zhang fixed this in the new Telemetry dashboard during his Summer 2015 internship