I'd like to create some time based posts on a specific channel and use the @channel functionality. I went into Teams and got the email address for the channel and then I've pasted it in the "Get an @ mention token for a user" function I get an error. It's a simple flow:

I've sent an email to that email address and it posts in the channel, so I know the email is correct. I've substituted my own email address in and run it and that posts, but it won't use the channel email to send a message to @channel. The error I get is "Resource 'c97db---------------------.onmicrosoft.com@ca.teams.ms' does not exist or one of its queried reference-property objects are not present."
Any ideas?
Thanks
Greg