Most streaming apps seem to have their own sources of the content. Whether they are sourced from the same feed as the networks' websites (and therefore, Channels' TVE feeds), or whether there is some adaptive multi-bitrate source (à la Netflix) that they are using, who knows.
The real point when troubleshooting TVE feeds is that you cannot use an app to see if the problem is consistent, or related to Channels. You need to check on the network's website, because that is the source that Channels uses. If the problem is present there, then there isn't much that can be done on Channels' end.
Also, a problem with one feed from a particular family of networks will usually appear in other channels owned by the same parent. For example, IFC and Sundance are both owned by AMC in your case. Another situation might be issues on History and Lifetime, both of which are owned by A+E Networks. (I frequently experience little jumps in the video needing to catch up to the audio on those channels; for the most part, the issue is the stream coming in to Channels.)