I have two similar vector layers, with the same attributes. One is multipart and I used it as mask for the atlas, the other one is single parts and I want to use it to label the polygons inside each multipart polygon.
I have tried with the rule based labeling with this filter
But it only works sometimes.
I tried to check all the label condictions, and I tried to do it with centroids to ensure that the point was inside the polygon of the mask, but no way to make it work.