I tried the RebuildPacletData[], but that was no help.
In[339]:= $Version Out[339]= "10.3.0 for Microsoft Windows (64-bit) (October 9, 2015)"
Anyone from Wolfram who can comment on this?
I don't have 10.3. Did you try to use the date objects format for the dates?
https://reference.wolfram.com/language/ref/DateObject.html