Came into this error myself. The error code -2003292288 is in fact WINCODEC_ERR_UNSUPPORTEDPIXELFORMAT (0x88982F80). The CreateWicBitmapRenderTarget method does not accept all WIC's pixel format.

My experiments on Windows 7 to 11 boxes have shown the method seems to accept the following WIC pixel formats for the original bitmap youwant to create a render target on (no matter what format you specify in the D2D1_RENDER_TARGET_PROPERTIES structure). As you see, there is no gray format:

8bpp Alpha (GUID_WICPixelFormat8bppAlpha)
 Guid: e6cd0116-eeba-4161-aa85-27dd9fb3a895
 Bits Per Pixel: 8
 Supports Transparency: True
 Numeric Representation: UnsignedInteger
 Channel Count: 1

32bpp BGR (GUID_WICPixelFormat32bppBGR)
 Guid: 6fddc324-4e03-4bfe-b185-3d77768dc90e
 Bits Per Pixel: 32
 Supports Transparency: False
 Numeric Representation: UnsignedInteger
 Channel Count: 3

32bpp RGB (GUID_WICPixelFormat32bppRGB)
 (Requires Windows 8 or Windows 7 with Platform Update)
 Guid: d98c6b95-3efe-47d6-bb25-eb1748ab0cf1
 Bits Per Pixel: 32
 Supports Transparency: False
 Numeric Representation: UnsignedInteger
 Channel Count: 3

32bpp pBGRA (GUID_WICPixelFormat32bppPBGRA)
 Guid: 6fddc324-4e03-4bfe-b185-3d77768dc910
 Bits Per Pixel: 32
 Supports Transparency: True
 Numeric Representation: UnsignedInteger
 Channel Count: 4

32bpp pRGBA (GUID_WICPixelFormat32bppPRGBA)
 Guid: 3cc4a650-a527-4d37-a916-3142c7ebedba
 Bits Per Pixel: 32
 Supports Transparency: True
 Numeric Representation: UnsignedInteger
 Channel Count: 4

64bpp RGB (GUID_WICPixelFormat64bppRGB)
 Guid: a1182111-186d-4d42-bc6a-9c8303a8dff9
 Bits Per Pixel: 64
 Supports Transparency: False
 Numeric Representation: UnsignedInteger
 Channel Count: 3

64bpp pRGBA (GUID_WICPixelFormat64bppPRGBA)
 Guid: 6fddc324-4e03-4bfe-b185-3d77768dc917
 Bits Per Pixel: 64
 Supports Transparency: True
 Numeric Representation: UnsignedInteger
 Channel Count: 4

64bpp pRGBA half (GUID_WICPixelFormat64bppPRGBAHalf)
 Guid: 58ad26c2-c623-4d9d-b320-387e49f8c442
 Bits Per Pixel: 64
 Supports Transparency: True
 Numeric Representation: Float
 Channel Count: 4

64bpp RGB half (GUID_WICPixelFormat64bppRGBHalf)
 Guid: 6fddc324-4e03-4bfe-b185-3d77768dc942
 Bits Per Pixel: 64
 Supports Transparency: False
 Numeric Representation: Float
 Channel Count: 3

128bpp pRGBA float (GUID_WICPixelFormat128bppPRGBAFloat)
 Guid: 6fddc324-4e03-4bfe-b185-3d77768dc91a
 Bits Per Pixel: 128
 Supports Transparency: True
 Numeric Representation: Float
 Channel Count: 4

128bpp RGB float (GUID_WICPixelFormat128bppRGBFloat)
 Guid: 6fddc324-4e03-4bfe-b185-3d77768dc91b
 Bits Per Pixel: 128
 Supports Transparency: False
 Numeric Representation: Float
 Channel Count: 3