Hi RB!
I was really quick on this!
Here the list from your Material.dat V2.021:
-These ones don't have alpha channel and also are now only a
tiny white image:
bubble_01, 02
bubbles_01, 02
casca1.tga ==> this one even don't open with Gimp.
ciob_add.tga
cloud_w_small_spots.tga
expl_hallo.tga
paraluie.tga
all pierreE*.tga
Smoke_volum02 and smoke_volum.tga
all splash*.tga (except splash_vert_add.tga only not have
alpha channel)
all twirl_soft*.tga
waterspray.tga
-Some others only don't have alpha channel (take a carefull look at all them)
-These ones have the same above problem but are also on the
texture folder, so no problems in the end:
cloud_w_small_spots.tga
paraluie.tga
some of pierreE*.tga
Smoke_volum02 and smoke_volum.tga
Notice that the textures from depth charges detonation splashes are in this list above. This is how and why I found this problem.
Hopes that this could help you!