I came across a bug/omission, perhaps in the update to 64bit.
C:\Program Files\National Instruments\LabVIEW 2017\user.lib\_OpenG.lib\variantconfig\variantconfig.llb\Write Key (Variant)__ogtk.vi
If you go to the case structure, the 64 bit datatypes (I64, U64, Enum U64, etc.) are missing. The result is that the default case is used and that parses the result incorrectly. It can be fixed by adding the 64 bit datatypes to the case structure.