Hi,
The session response and userCtx.channels field is only showing channel grants for the user directly, and not channels inherited through an assigned role. Notably, it is also only showing the default collection access - if you were to use any named collections they would not be represented in this response either.
This role one specifically it does turn out to be a bug, but a very longstanding one that in reality doesn’t actually break anything. It’s just confusing to see. I’ve filed an issue and we’ll likely get a fix for this into an upcoming release.
Actual document/changes feed requests do evaluate channels with role inheritance so although it looks like the session isn’t valid for those additional role channels, in practice they will be.