I have tried updating my local <nixpkgs> directory with 'nix-channel --update'.
No change; the full nix-instantiate command does not terminate.
The git commit of <nixpkgs> (in /home/paul/.nix-defexpr/channels/nixpkgs/.version-suffix) is now 497e6d2.
Also, if I remove '--strict' from the nix-instantiate command I get:
<?xml version='1.0' encoding='utf-8'?>
<expr>
<derivation>
<repeated />
</derivation>
</expr>
Terse! but at least the process completes.
I have noticed that the non-termination problem is not confined to the opencascage_oce package. If I try
$ nix-instantiate --strict --eval --xml -A guile /home/paul/.nix-defexpr/channels/nixpkgs
that does not terminate either.
Best,
Paul.