After analyzing the tracer log for the onclick event of the Basic menu noticed that @baseclass.ProcessAction activity is being triggered. In this activity at step 18 it is calling @baseclass.PerformPreProcessing activity which is loading the D_BasicPaletteDetails data page. pyPaletteOptions property holds the information that will be displayed on click of the Basic menu in your section.
So you can try to trace the functionality and check the behavior at your end or try to run the D_BasicPaletteDetails data page directly to check the data in the pyPaletteOptions property in it.
I also had a member from the PEGA Support Team provided a solution and it worked. The following DSS settings need to be added to rectify SQL query performance issue in the back-end database and resolved the missing UI elements issue.