The NVTT exporter seems to mess up loading DDS images with the B5G5R5A1_UNORM pixel format (see screenshot below).
Interestingly, B5G6R5_UNORM works just fine.
(I’ve verified the DDS file is valid using Paint.NET.)
Addendum:
B8G8R8X8_UNORM - produces a fully transparent image. I guess the X8 is meant to mean fully opaque, not fully transparent :-)
B8G8R8X8_UNORM_SRGB - errors with “DXGI format 93 is unsupported.” Should this be consistent with the non-SRGB format?