I have a similar problem.I recently bought a new Denon AVR home theater receiver for the house. It also has BT. Now when I roll the bike out of the garage and connect the Cardo with my phone for music, it connects to the Denon in the house! I have to go down the street a bit to get my music and Cardo working!
If the wife is driving the car and I'm relatively close on the bike, I can have a conversation with her (PacTalk Bold and in car BT).
I haven't figured out what's causing it, but it's likely the BT mesh system on the PacTalk. It's kind of useful for us, so I've not really tried to fix it.