You're correct to state V6 boxes did not behave like this, those all had their own hard drives. 360-boxes are either masters (with hard drives) or minis, that rely on the master for all recording due to not having HDD's of their own.
So all your recordings are actually being stored on your 360-master, and the mini is multi-room streaming all its recordings from the master. This is by design of the TV360 system, which fundamentally is different to TiVo/V6.
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