Open up the customise dialog, select the upper (or lower) left quad, in the list expand one of the entries, highlight one of the sub-entries > right-click > Edit Macroscript.
That should show you how the quad menu item is enabled/disabled and whether a suitable object is selected. Check a few of them as many have different criteria.
Note. Don't edit that file without making certain you have a backup first! If in doubt, cancel any changes when you close the editor.
Max 2016 (SP1/EXT1)
Win7Pro x64 (SP1). i5-3570K @ 4.4GHz, 8Gb Ram, DX11.
nVidia GTX760 (2GB) (Driver 430.86).