UPDATE - It looks like this temporary fix of using the app on your phone doesn't work any longer. (posting on Feb 5, 2025). Really unfortunate as now the best way is to use "Create a Team from Template" > Select the 2nd option "Manage a Project" - which shows the "General" channel > and then go back and delete the extra channels that it automatically creates.
NOT A GREAT SOLUTION - when the "FROM SCRATCH" option should include the GENERAL channel as its default and primary channel.
REALLY FRUSTRATING that this continues to be a problem.
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Here's an easy fix - USE THE TEAMS APP ON YOUR PHONE (not the desktop) - and it will only ask you to name the "Team" and will automatically add "General" as the first channel.
When using app on your Phone (for now, until Microsoft messes it up further) - you only have to enter the Team Name, and General Channel is set up automatically.