when I try to compile the design using :-
ncvhdl -CDSLIB cds.lib -WORK work <design>.vhdl
First make sure whether you need to compile everything under the "work" library (which is the default).
There are many cases in which VHDL modules need to be compiled to some other library (which exists as a folder inside your simulation dir, in your case a folder named "x") which is NOT work.