@Ian *********
Some but not all immigration offices interpret it this way, but it makes sense in a way.
With a re-entry permit you are still on the same stay, you only interrupted it.
But you can always try to submit online, when you receive email it is rejected, you can use the already completely filled in TM47 report and bring it to the immigration office.
They will not punish you because you filed online, so maybe you are just lucky.