It maybe just timing out, if you have all three tuners configured they all need a feed,
so if one of your sat tuners A or B hasn't got a coax connected you can get an error.
I assume cable Tuner C has normally got a push fit connected to it.
If one tuner hasn't got a feed set it to not configured.
That error you are showing is usually down to a bad connection if all the tuners have a feed.
Just connect one tuner and set the remaining two to not configured.
Then run ABM to see if you can work out which one is causing the problem.