GridLines in TimelinePlot do not export to EPS

Question

The below TimelinePlot produces the proper figure within a Mathematica session, but when that figure is exported as an .eps figure (to be used in a $\LaTeX$ document) all portions appear except the vertical GridLines. (They do appear if the figure is exported as a BMP format as shown below, but that format cannot be integrated into a $\LaTeX$ document under the $\LaTeX$ version I'm running. I prefer .eps format for a number of other reasons as well.)

I'm using Mathematica version 10.1 under OS X on a Mac Pro.

timeLine = TimelinePlot[{
   {Labeled[Interval[{{2016, 1, 1}, {2016, 6, 15}}], "aaa"], 
    Labeled[Interval[{{2016, 2, 1}, {2016, 5, 15}}], "bbb"],
    Labeled[Interval[{{2017, 5, 5}, {2017, 8, 1}}], "ccc"]},
   {Labeled[Interval[{{2017, 4, 15}, {2018, 1, 1}}], "ddd"],
    Labeled[Interval[{{2018, 4, 15}, {2019, 1, 1}}], "eee"]}},
  PlotRange -> {{{2016, 1, 1}, {2018, 12, 15}}},
  GridLines -> {Automatic, None},
  GridLinesStyle -> {{Dashed, Green}, None},
  PlotStyle -> {Blue, Red},
  Spacings -> {1, 5},
  PlotLegends -> Placed[{"AAA", "BBB"}, Bottom],
  ImageSize -> 700]

How can I get the GridLines to export in the .eps format?

Answer 1

Figured it out. For some unknown reason, GridLines created with DateRange and Quantity magically export in .eps.

 GridLines -> {DateRange["2016", "2019", Quantity[3, "Months"]], None}

I have no idea why this form works while Automatic does not.