When I do importprivkey xxx, I get this error: vector::_M_range_check (code -1)
Do you import successfully after the error ? or It shows error, and doesn't let you import ?
When I do importprivkey xxx again, the error is now: Error adding key to wallet (code -4)
I always add the private keys twice (use up arrow). When you get error -4 that's exactly when the address shows up on your list.