Something wonky must have happened. I've been seeing many complaints related to MRV and TTG pop up recently.
I was trying to do some MRVs yesterday and Tivo 1 couldn't see the recordings on Tivo 2.
Long story short, I rebooted all my Tivos at the same time. When they came back, two of them had reverted back to not allowing transfers. I had all Tivos phone home and got things working again.