Its not bug actually.
HG antennas cant relay signal. Its intended behavior. But to establish a connection, both sides must have sufficient range, and so HG antenna in the moon's orbit can not establish a connection with the LG antenna in the LKO.
Previously, this system worked well. But now, when we have these awesome ground stations - no longer. The range is sufficient only for KSC.
I have made simple test - modified configs so all antennas become LG, in these case signal network works just fine.