RDKit Optimize Geometry CTD with MMFF

I'm getting RDKit Optimize Geometry Crash To Desktop with MMFF94 or MMFF94S.

No error messages. Knime 2.9.2 nightly build on Windows 7 64-bit.

It may well be crashing on a "weird" input molecule, but I have no way of determining which one(s) are causing the problem.

I believe that the RDKit libraries are built-in, but is it possible to point the RDKit Knime nodes to a use an external RDKit library?

Cheers,

Steve.