Any ideas on how to do this? For example, I have something in my feed I want to play using the FX Channel, but it doesn't show up as an option...
I suspect it has to do with which channels supply their guide information to Roku.
"My Feed" may also be (temporarily for a week or three) unavailable due to the Olympics Feed replacing it in the UI.
You can always complain about this to Roku: https://support.roku.com/contactus/contact-options (choose setup/ultra/other/need more help?)
..and suggest it as a feature: https://community.roku.com/t5/Suggest-a-Feature/bd-p/Wishlist