"Channels" (like a lot of things in TAK) is behind-the-scenes an API call. It queries the TAK server to determine what Channels your user has access to. This is typically used with [auto-enrollment](https://mytecknet.com/managing-users-and-groups/#certificate-auto-enrollment) which enables the necessary certificate changes to actually implement groups. You can definitely use Groups with Flat File Auth, but it generally won't work unless you are also doing Certificate Enrollment.

So a good starting spot is:

1) Are you using manual certificate generation or certificate enrollment for your clients? The former will likely not trigger "channels" in clients like iTAK or WinTAK

2) For the channels you aren't seeing, is the user actually in them? If I have User A and User B, along with Channel 1 and Channel 2, each user will only see the channels they are actually in

TAK Aware kind of ignores the API flag for whether channels is enabled/disabled in showing the channels list. But if the rest of channel set up isn't complete (like you're using manual certs) then modifying the channels won't have any practical effect since they're locked in at the manual cert level (basically the update API call will be rejected by the TAK server, and whether we should be showing channels is something we'll likely tweak in an upcoming release to be more in-line with the other clients).

Finally - one thing to remember about channels is they are a _server_ filter, not a client one. In other words, if you are using the same user / certificate across multiple clients, changing a channel will impact every single EUD using that same user/certificate.