So my understanding of the description is that if I have 2 levels of Wizard and choose the Evocation school, then when I cast Evocation spells they won't deal damage to my allies and any saving throws required will automatically be passed by my allies.

In my testing a few minutes ago (as I've finally tried this out) the follows spells gave these results:

Moonbeam (Evocation): Allies were damaged by it

Ice Storm (Evocation): Allies took no damage, 3/4 saved against the Ice prone, 1/4 failed the save and went prone.

Wall of Fire (Evocation): Allies took damage

So I think I've clearly misunderstood something but every time I read the description of Sculpt Spell I find it hard to understand it any other way.

Is this a bug issue or is it my misunderstanding? :/

Edit: huge thanks to u/dragonseth07 and u/Ndog921 for asking questions I wasn't thinking of which made me reconsider the situations and the specifics involved. Wall of Fire's spell damage seemed to not affect Wyll, but the fire surface did, makes sense. I now realize Moonbeam is a "surface" as well as people can walk into and out of it. So Sculpt Spell obviously doesn't affect surfaces, which is a shame, but now I think I finally get it!