A macro that has no triggers can still be executed in a number of indirect ways, such as via the Execute a Macro action, via AppleScript or a Palette or the web server.

So it is not required to have a trigger, however if you have no explicit trigger you will not be able to trigger the macro directly. That is fine, if that is your intention, but if you are expecting to manually trigger the macro you will probably want to add a trigger to it.

If you continue to have problems, contact support.