So when I'm sending a command to RFDATA through RF, I always receive the ack (sometimes several times, as I'm in range of multiple TX Igates) but most of the time I don't get the actual answer. They are correctly sent to APRS-IS (as can be seen on aprs.fi) but they are not gated to RF somehow.
One hypothesis might be that if the ack and the actual answer are sent simultaneously, the ack gets gated through RF as it comes first, but the answer is skipped as the Igate is already busy transmitting the ack.