MCelliotG is correct; these muxes are in S2X, so a card with an S2X extension is recommended.
And yet, the signal can also be seen and locked with the 6983 cards, which do not have this extension. I indeed used the IQmonitor app for this purpose.
If you see a signal trace, I repeat what I said in a previous post, i.e. work on the elevation, without changing other antenna parameters. About an inch or so is needed to raise the reflector to get a maximum signal. This, of course, depends on the size of the antenna.