If I copy paste the example with nd_export_plt() as provided and run in Spyder it shows the plot in the Spyder plot tab (Spyder4), as expected and shown in the post. If you do not see it, do you see any matplotlib output outside Nazca?
If I copy paste the example and *replace*
nd.export_gds(C) it exports the gds as expected.
Starting layout export... ...gds generation ...Wrote file './nazca_export.gds'
nd_export_plt(C) # the C is needed as cell C is never put() in the example. # alternatively: C.put(0) nd_export_plt() # export the nazca main canvas having C on board.
If you keep both plt and gds output commands you have to check the notes below.
nd_export_plt() # deletes/resets the canvas after export nd_export_gds() # nothing to draw
nd_export_plt(clear=False) # does *not* delete the canvas nd_export_gds() # now generates full gds