Ground targeted spells with single target aim assist (Magmus Lava Surge, Pyro Phoenix Wave, Fayde Burning Shadows, Wretched Hag Bat Blast, Behemoth Fissure) all show "This is not a valid target" on buildings and catapaults (both friendly and enemy on both instances).
Not reproducible on replays. Must test in-game.
The idea is the same as with the ally targeting fix. The building / catapult / ally is in the way of the ideal targeting point on a spell that is primarily for AoE rather than single targeting.
I'll confirm it - targeting system should be reworked so that it essentially ignores any invalid units for target_dual_position spells
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