What type of Blending are you using for the 2 materials? In Landscape paint mode, Weight(Can be overridden) vs Non Weight(Can’t be overridden) both works differently than the blend mode in the material itself.
This video How to Paint Landscapes in Unreal Engine 4 - YouTube should get you started, When Confused use layer debug [ViewMode->Visualizers->LayerDebug] and then check different colors for both layers and see if it helps.
I love making Single Player games, mostly RPGs. I’m a programmer mainly but I do love environments as well and a bit of UMG.