Discrepancy in decals rendering when upgrading from UE 5.0 to 5.1

I’ve updated my project from UE 5.0 to UE 5.1 and now the decals I’ve been using are not rendering correctly.
I’m using the Quixel Megascans - Blood to decorate the interior of a train car. The scene looks like this in UE 5.0:

But in UE 5.1 the decals are missing their color, and now looks like they are see through:

The material looks fine (afaik.) Could it be lighting related?