Unity is overwritting UV1 when generating lightmapping UVS?

I've imported a mesh with two UV channels. One for the texture UVs, and one for the decal UVs. That is the options given in the Standard Shader, right?? (UV1)

So when ticking generate UVs, Unity is overwriting the secondary decal UVs with the lightmapping UVs?
How to use primary, secondary decal UVs, and lightmapping UVs simultaneously?


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