I am missing channels on this app: History, FX, FXM, National Geographic, NatGeo Wild, Disney
Some channels don't have streaming capabilities and thus won't work with Channels. History is one such channel. The other ones you mentioned should work though. Maybe someone else can help.
Channels DVR relies on TV Everywhere (TVE) to access the streaming content. Not all channels are available via TVE. The list varies with each provider. Some networks (like History) don’t provide a live stream via the web at all.
Click the pencil to view the channels in the TVE section. In the upper right of the channel list, choose "edit". Scroll down the list to the missing channels and see what is being reported. As mentioned, History does not have a live stream so it will not be there, but the others should.