I dont think it's going to sleep, it could be software issue and not MB (though I've done a factory reset for other reasons and this issue is still happening) but it's so weird it works the second time.
When I do the first sync, nothing is copied over, it just hangs until it fails or I close out, BUT it will remove any file I have marked for deletion.
I've even removed the device and readded it to MB in preferences.
Only thing I haven't tried yet and I'll probably try this weekend is wipe my sd card and sync everything over. There could be some android file on there from an older ROM I was on as I've been syching to this memory card for a year and a half through up dates and different roms, so it just may need to be wiped and start from scratch