daveyj
You didnt mention your Roku model # or firmware version (Settings/System/About) or app version (highlight the app and press Options (*) on the remote).
You can try reinstalling the TCM app:
1) Remove the TCM app (Highlight the app, press the Options (*) button on the remote, then Remove)
2) RESTART the Roku (Settings/System/System restart/Restart) <-- MUST DO THIS HERE!!!
3) Re-install the TCM app
(If you dont restart after removal, settings/cached data associated with the app are left behind and it wont be a clean re-install)
However, reinstalling isnt working for many users, especially those with older models:
https://community.roku.com/t5/Channel-Issues-Questions/Watch-TCM-not-working-after-July-15-2021-update/td-p/705568
https://community.roku.com/t5/Channel-Issues-Questions/Cannot-access-TCM-format-changed-will-not-allow-me-to-sign-in-Anyone-else/m-p/716256
Make sure you report the TCM app not loading to Roku:
Highlight Watch TCM,/Options (*)/Give us Feedback/Channel failed to launch
And to TCM:
https://tcmdigitalhelp.zendesk.com/hc/en-us/requests/new