I have seen that message when my return power was too high and only could only use 2 channels out of 3. Your modem will then warn you about partial channels (or something like that). Now that's something more worth your attention.
This is just a formatting issue that they just print some junk in the empty box when the entry is not used. Blame the lazy programmers. User reactions are why they really dumb things down these days.
As others have pointed out the fact that it says Frequency 0.0 MHz tells you the channel is not being used.
Technical info about modulation follows ...
The Modulation defines the way the digital signals are encoded on a radio type signal to decode them correctly. There are many but in the cable world, the two most common are now QAM (Quadrature Amplitude Modulation) and QPSK (Quadrature Phase Shift Keying - keying comes from the old daze of morse code which is sent by "keying").
These techniques are based on progressive mathematical transforms that allow more data to be encoded. The simplest "keying" (On-Off keying) resulted in the speed or frequency being identical ... a 100 Hz signal could convey up to 100 bits / second.
4 QAM will produce the same mathematical transforms as QPSK although derived differently from the maths!
The higher the QAM number, essentially the more bits per Hz can be sent down the cable. For example a 6 MHz DOCSIS channel at 256 QAM can transmit a total raw throughput of 42 Mb/s ... i.e. about 7 bits per Hz.