The signal is going to be weaker than a direct connection unless you are lucky enough to have really great signal on all stations to begin with. That's true for homeworx and iview. I bought a five buck splitter at best buy and get better signal with that than using the loop through.
The only working when off thing is weird though. Curious what firmware your unit came with - that's the easiest way to determine what hardware version you have as well.
I'm wondering if you got one of the units that work when off and then the homeworx is causing too much interference when it's on.
mine came with firmaware V13 - hardware 7816-atsc-03