Problem with Netflix DRM - CID 42

I’ve recently installed IceDragon 42 and I had no problems until I tried to play Netflix. Whenever I log in I get the following message:

The audio or video on this page requires DRM software that IceDragon does not support.” followed by a “Learn More” link, which leads to a “page not found” message. Searching on icedragon, DRM and netflix didn’t give me any solutions.

I checked if DRM is enabled in the settings (it is). If (for testing purposes) I disable it, then I get a request to turn it on again, which in turn just leads me to the above message again.

I’ve also tested it on a different machine and tried turning off addons like noscript, uBlock and disconnect, but it didn’t matter.

Netflix works fine on (the latest versions of) both Opera and Palemoon.

Is there a setting I’m missing?