Clean install of NMIS 4.2.12 using supplied sample config files. No "Links" button appears in top toolbar row next to DNS button as it should.
Changed "links" to "link" in button field of toolset.csv file to correct issue on my system.
There are two (2) links buttons in the default toolset.csv file. The first one is for the Links button that is in the top 'action' toolbar and the second is for the Links button in the 'table' toolbar which functions properly.