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LightmapUVs material node is buggy

The LightmapUV node works only for a single mesh. So it is like for every mesh that you want to apply the material to you need a new Material.

Here, the same material is applied to all the meshes but only the back wall shows this distorted alpha noisy mask which is done with LightMapUV in the material:

is the issue the same if you set the coordinate index to whatever your lightmap UV channel is in the texture coordinate node?