as you can see the mapping is has keyframes but they do not show up in the graph editor
you have to select the mapping node, then it should show up. If not, pls provide blend file
there seems to be a bug in show only what is selected in the graph editor
turning that on makes all visible
That is not a bug, but a feature. In this way, you can animate what is selected. Otherwise it would be very crowded in the graph editor and impossible to select the keyframe of your object. Several keyframes would overlap.
The show only selected shows nothing
Even when selected !
maybe provide your blend file so we can help you exactly instead of guessing?