Unable to load textures from Fallout 76, except luminance maps.

[ryandenki]

I've tried with both Photoshop 2020 an old copy of CS6, and although saving newly-created files works fine, I cannot load most FO76 textures except luminance maps.

Could not open "...dds" because Can not load image..

Every file. Except luminance maps, which are fine. Have tried the CC version, the CS6 version, 32- and 64-bit versions of each.
All of the four plugins in both versions of Photoshop give the same error. Windows 10.

Anybody encountered this before?