If I tick show only visible, I get no features.
I have created an attribute table in the Map Composer in QGIS trunk QGIS version 1.9.90-Alpha QGIS code revision 4d6cc6d I note recent feature update http://hub.qgis.org/issues/4496 but this doesn't explain my experience. I suspect it is misuse on my part.
I would like to select a feature in the main attribute table in QGIS, then have it show only the label for that feature and show only that row in the attribute table in Print Composer.
I explored the options considerably I think, when I uncheck the box I get as many rows as the setting will allow, no relationship to visible. I have checked the Map 1 in the dropdown.
I have written this much, maybe it will help someone else... I am going to explore reloading the layer, it is in fact a delimited text layer since I am using the read only status of that layer to provide some versioning control. Will see what happens when I reload it as a shapefile.
This is cutting edge cartography as far as my skillset is concerned....