ExodusII reader having problems with 18 node prisms/wedge
There are two issues here. The first is that the 18 node prism/wedge is being read in as a 6 node cell. Can see by looking at one_prism18.e with ncdump that it is indeed an 18 node cell. For two_prism18.e the connectivity seems to be wrong. See the discussion at https://github.com/libMesh/libmesh/issues/2882#issuecomment-805862325.
Note that both files are completely open and can be added as test files if needed.