Where can you activate GI?

Well try No-Precomputed Lighting" checkbox in “World Setting” first as this should give you a complete GI solution, or at the very least point out what needs to be changed as light baking will no longer occure

If using sky light along with a directional light I wquld also suggest turning off cast shadows on the sky light as it tends to shadow fight with other GI based lighting tthat also cast shadows.