Tvheadend

Is EPG data based on Network ID or Mux ID? I live in a region where two different MUX are owned by the same company (see image attached) and even though they have different frequencies the Network ID and Mux ID are identical. One of the MUX works fine however on the other other MUX I can watch the services OK however no EPG data will download for these channels?

A few stats:
OpenElec 12.2 Frodo - generic build on old pentium 4 box
HTS Tvheadend 3.4.27
Tvheadend HTSP Client
Hauppage Nova 500 dual DVB-T tuner
Australia DVB-T