1. from foxHelp project information dialog box and relative to vfp supported Icons:
To display the icon correctly in the Windows Explorer, the icon file should contain both 32 x 32 and 16 x 16 icon images.
The 32 x 32 image is used in the Explorer Large Icons view, and the 16 x 16 image is used in the Explorer Small Icons, List, and Detail views.
The following table lists the icon image formats that Visual FoxPro supports.

Colors Size (pixels)
True Color (24 bit) 16 x 16
True Color (24 bit) 32 x 32
True Color (24 bit) 48 x 48
True Color (16 bit) 16 x 16
True Color (16 bit) 32 x 32
True Color (16 bit) 48 x 48
256 Color 16 x 16
256 Color 32 x 32
256 Color 48 x 48
16 Color 16 x 16
16 Color 32 x 32
16 Color 48 x 48

NB: you icon is 32 bits 16x17 try to convert it to 16 bits 16x16 or 32x32 and re test.

2.in my windows 64 bits mscomctl.ocx (1046 ko)
C:\Windows\SysWOW64

3.loadpicture is vfp native function.its exists even from vfp 5,6.its Creates an object reference for a bitmap, icon, or Windows meta file.
its used to load an icon to imagesList,treeview controls...
Icons are allowed with sizes up to 128x128 and must not have more than 256 colors. Even if there is more than one icon stored in the icon file, always only the smallest icon gets displayed.
The icon file may contain much more icons - even with more colors and larger sizes - as long as there is at least one that complies with the rules above, then no exception is thrown.

maybe it derived from gdi32 but not gdiplus.
in my windows64 bits gdiplus.dll (1623ko) is located at:C:\Windows\System32

update:
the loadpicture vfp function seems to be a wrapper of OleCreatePictureIndirect() WINDOWS API (OleAut32.dll)
from;
https://myvfpblog.blogspot.com/2011/04/loadpicture-functionsome-myths-revealed.html
its also described in foxhelp:as:{LOADPICTURE( ) Function internally wraps the OleCreatePictureIndirect() function implemented in OleAut32.dll. )