bugs - Strange Error on Fresh Kernel (10.2)

Bug introduced in 10.1

I wrote a helper function to format real numbers in a certain format for writing .dbf files here. It relies on a new function to 10.1 - StringPadLeft.

Here's that function:

realformat[num_] := ToString@ScientificForm@PaddedForm[num + 0., {12, 11}, 

 NumberFormat -> (Row[{#1, "e", If[ToExpression[(#3 /. "" -> "0")] < 0, "-", "+"], 
 StringPadLeft[StringReplace[ToString@#3, "-" -> ""], 3, "0"]}] &)]

SetAttributes[realformat, Listable]

realformat[{56023.3, 16, -1523532.1}]

{" 5.60233000000e+004", " 1.60000000000e+001", "-1.52353210000e+006"}

However, the first time this is called (ie on a fresh kernel), I get the following error:

Get::noopen: Cannot open C:\Users\username\AppData\Roaming\Mathematica\Paclets\Repository\GeneralUtilities-10.2.1\Kernel\ 64.00000000000Bit\GeneralUtilities.mx\

And the output is as such:

{" 5.60233000000e+StringPadLeft[4, 3.00000000000e+StringPadLeft[, \ 3.00000000000, 0], 0]", " 1.60000000000e+StringPadLeft[1, \ 3.00000000000e+StringPadLeft[, 3.00000000000, 0], 0]", \ "-1.52353210000e+StringPadLeft[6, 3.00000000000e+StringPadLeft[, \ 3.00000000000, 0], 0]"}

Oh dear.

Now I can navigate to the folder C:\Users\username\AppData\Roaming\Mathematica\Paclets\Repository\GeneralUtilities-10.2.1 and manually run the GeneralUtilities package, which solves the issue, but that's rather annoying. All file permissions look okay and I've tried resetting all settings to no avail.

Anybody have a solution or is this a bug?

$Version
10.2.0 for Microsoft Windows (64-bit) (July 7, 2015)