I don't know for certain if this is a bug with Step Skyrim SE, but thought I'd report it here just in case.
Starting with a fresh installation of Step Skyrim SE 1.0.0, I added ASIS immediately after. Running ASIS fails because Skyproc identifies a missing master: "LRR - Alternative - by LeonardoTrote.esp". This ESP comes from this mod: Lucien Lachance Restored - Immersive Spectral Assassin at Skyrim Special Edition Nexus - Mods and Community (nexusmods.com)
Installing that mod--with the correct selection of the "Alternative" rather than "Classic" style--resolves the issue.