According to this, they should work
Click on a Check Availability link for one of them and see if the Network website lets you login with your Sling credentials and stream it.
If that works, it's a problem with your Channels DVR server.
See TVE Troubleshooting tips
I've got a Sling TV Blue subscription entered as a source in my Channels DVR setup....
Right now, in the Sling app itself just via the internet (w/ no antenna), I get the local channels for ABC, NBC and Fox (because I'm in one of the select large metro market areas), the NFL Network, and a ton of other various cable and free stream channels.
However, within my Channels DVR setup, I get very little from Sling via TVE: My Fox local channel, nothing from my ABC or NBC locals, no NFL Network. Used to get USA Network, but it's now gone.
But I do get these other channels via Sling TVE in Channels DVR: FX, A&E, History, Lifetime, Nat Geo, and Fox News.
Along with a long list of lesser known channels that, if I understand right, are sourced from Channels DVR to me because I'm subscribed here and have a pay TV account?
All the TVE channels 6700 and up are included "freebies" no matter what provider you authenticate with. They are freely available without authenticating via a provider.
Sling has the worst TVE support among the supported providers. You can see the list supported by Channels DVR here Channels Support - TV Everywhere Availability
From About TV Everywhere
Thanks for the clarification about the Channels DVR-provided channels NOT requiring an external paid TV provider account! 
The Sling TV list you linked to in Support is less than useful, considering that virtually every potential channel on the list presented there is labeled with "Check Availability"
I understand that may be in part because Sling has two different service plans, Blue and Orange, with somewhat different channel lineups in each. But I believe there are at least a small set of common TVE channels available in BOTH plans that thus would be available to all Sling subscribers, AFAIK.
I find those lists useful. If you know how Channels DVR TVE works About TV Everywhere
Click each one to be taken to the Network website where Channels DVR gets its stream from, authenticate with your provider and see if it streams. If you can do that it should work using the same provider authentication in Channels DVR. If it fails, it won't work in Channels DVR.
I'm experiencing the same problem at the moment. I'm About to throw my arms up in the air. Although I can login on all other devices, just channels is having an issue.
If you are using Sling, TVE is dead.
No reason to mess with it.
As usual, not much is supported through TVE with Sling: currently with Sling Blue I can get the following in Channels:
A&E
FYI
Lifetime
NatGeo
NatGeoP
Fox News
FX
FXP
FS1
Looks like you are getting a portion of the channels on Sling.
Seems like the best option for TVE is Fubo.
Most of anyting worth while is unlocked.
Unfortunately the plan costs a lot but you can get what you want.
Yttv is good
Things are expensive no matter how you cut it.
I am not getting listings for the Dove channel. Is this a Sling issue or Channels?
My XFINITY Dove says "To Be Announced"
And now I have them. Seriously, I did not have them for days.
Replying to the post from Nov 23. Just thought that I would add that you also get History, FXM,FXX, and FS2 in Sling TVE if you have those add-ons.
So...who else took advantage of the 200 bucks for 4 months deal?
The TVE options are anemic but still usable for me (ESPN and FS1 is there) and I got my HDMI encoder coming in (and i got an old firetv on standby) so that'll help ease problems.
Gonna be my goto during football season
I might do this, but waiting a few more days so that 4 months will carry all the way through the CFB national championship. Yeah, Sling's TVE availability sucks but I can always watch through their app if I have to.
Planning on the same thing. To me, it's also about maximizing Hockey season.
Yeah...I took a bite earlier to watch EPL games but yeah. I'm still good until Boxing Day (which is fine because my Giants may be on TV here in Miami or eliminated from the playoffs)
I have the Sling TV Blue plan in one of the major O&O media markets, and I'm getting very little of any value via TVE within Channels DVR anymore.
I used to get my local NBC affiliate and my local Fox affiliate in my major market city. First the NBC channel access disappeared a long time back, and now more recently, I still show a channel for my Fox affiliate within Channels, but it doesn't actually play any content when I click it.
Within Channels, otherwise, I can still access A&E, History, Lifetime, FS1, Comet, and some misc. news and sports channels that I believe Channels itself provides to subscribers.
Yet for some reason, with the same Sling TV Blue subscription, I still get my local Fox and NBC affiliates via my Stremium / Fitzy subscription, and both play just fine there and always have, along with numerous other regular cable channels via my linked Sling subscription.
Those use different sources than Channels do. Channels uses the site to get the feed (ie. FOX fox.com) but streamium and sling gets it direct from the broadcasters usually.