roughness RGBA mask square patters appears random using RGBA masks

[Ebalestrini01]

-Hello guys, I am having problems with the rough map in this project .
this a nanite mesh with a RGBA mask texturing in virtual textures , everything was working fine but i got this squares patterns into my roughness map , looks like some time optimization or don’t know why is doing this the other maps are fine a looking good just the roughness map when i add the mask it breaks the material roughness this way . in my RGBA masks I got into BC7 DX11,optional A . I think is something related with the compression of the RGBA masks if i change to HDR Compressed RGB,BC6H,DH11 the problem don’t look that bad it’s harder to pick in rendering mode

i am using path tracing for render the mesh are fully nanite ,
my RGBA mask are using UDIMS to get 40 pixels cm texel density
when i add the Mask this squares pattern appears it will not show with a simple material without the masks
this square patterns move and appear and disappear when I move around the geo .

i suspect the problem it’s coming to textures compresion , any help advice will be helpful
it’s just on the rough map !

attaching the problem image

[Ebalestrini01]

This has some to do with the alpha channel. If you kill the alpha channel with this option the problem
stops. no more weird parts in the roughness map , i suspect that leaving that chequer pattern because the alpha channel is being read some kind of transparency created the problem, it’s very weird not being able to use 4 channels of RGBA mask with this issue.
If anyone has any idea how to keep the 4 channels and not get transparency in the textures please help.
i am using RGBA mask through material functions anyone have any idea

not sure if I am posting in the right place to have an answer

Looks like there is bug between that chequer patter coming from the alpha textures
is there is way to engine take it like black and white to be able to use the mask
The solution it’s somehow unreal: don’t disappear the texture with chequer pattern behind and don’t read as transparent instead just read alpha channel black and white like any other channel.
does anyone have any idea how to do that ?