I never thought the meter was "in" the circuit breaker box. The documentation shows it is intended to be a form-fit-function replacement for the old mechanical meter.
Our main exterior disconnect panel that feeds all 240V loads and several 120V circuits also has the meter plugged right into it. If the passive coupler was installed in that type of panel, it could easily have been removed by the contractor who changed the meter.
The question I had was what kind of communication is used between the utility company and the new smart meter. The Siemens smart meter uses a spread spectrum technique spanning from 9 to 500KHz. Since that overlaps the X10 frequency, it might cause a problem. While this particular meter does not support communication directly, a separate communication module referenced in the documentation works in the 900MHz range. That certainly would not be an issue for X10 communication.
The original poster said he thought there was a phase coupler installed, but it now appears to be missing. Since it is unlikely the meter is the cause of the problem itself, I suspect the problem may be due to the possible removal of that phase coupler by the contractor who replaced the meter.
Of course, the meter does contain electronics. It might also contain a surge protector that is a signal sucker, attenuating an already weak signal to the point it no longer provides reliable control.
Jeff