Exporting layer masks as grayscale (not indexed color)

[jaakkos41991595]

I have several multi-UDIM model I am working on and I need to export grayscale layer masks from Substance Painter to Unreal/ You know, to get ability to change color in Unreal based on the mask and such.

So, if I right click a layer and "export mask" this will export the masks in UDIM format, but the resulting bitmaps are indexed color, not grayscale. And this is problem. This will not work in Unreal, as I am getting "Warning: Mismatched UDIM image formats" if I try to load them to UE.
I have tried manually to convert the maps to grayscale and this works, but obviously hand converting each map after export will destroy the workflow.
Any recommendation?