Ex Nihilo Creatio has the following option:

    # If enabled, all meshes can obtain the results from the lower tier meshes.
    # Note if the same item is registered in multiple tiers, then the higher tier
    # will have a chance to drop multiples.
    B:flattenSieveRecipes=true

From what I've seen so far, that doesn't apply to Heavy Sieves if the setting is true. Which basically means I have to waste a lot of diamonds for meshes to make the normal sieves efficient enough and then the Heavy Sieves are kinda obsolete.

So, I wish Ex Compressum would adapt that setting, maybe with an config option to enable/disable it.

i can confirm it is also a problem on the normal auto sieve too

hope you can fix it