10-29-2014 06:20 AM - edited 10-29-2014 06:26 AM
The Get Date/Time function uses internally an old function that is limited to U32 only. The other Data Time formating functions where overhauled in LabVIEW 8.0 or there around to work with the full 128 bit timestamp data but the Get Data/Time function missed that boat, possibly because the function was considered legacy.
It should not depend on 32 bit or 64 bit LabVIEW but there is a chance that they fixed in in a later version than 2011 anyhow to at least use U64 as base (no fractional part is strictly necessary for the Time string). I would test it on 2014 if I had it installed here.
Also I'm not sure where the reference to U64 for this function would be that was mentioned earlier. In my local 2011 installation online help there is nothing about U64 mentioned in the help.