Actually, EnvelopeNOW does allow you to move the OMR outside the allowed area (although it really isn't recommended to do so!) but in this instance, it sounds like the customer wants to rotate the OMR so it fits alongside the short edge of the page, which is not something EnvelopeNOW allows.
My answer doesn't help the customer in any way, I simply wanted to clarify the behaviour for future reference.
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Technical Product Manager
I don't want to achieve immortality through my work; I want to achieve immortality through not dying - Woody Allen