Sure thing. I just did this and recreated these 10 steps to reproduce the bug from a brand new paper2d project using the starter content assets.
Step 1: Create a new 2D side scroller project. I included the starter content for this project.
Step 2: Open the 2DSideScrollerCharacter blueprint and set the
SideViewCameraComponent to Perspective View(needed for real time lighting)
Step 3: While still in the character, set the sprite material to MaskedLitSpriteMaterial( this automatically comes with a flat normal map).
Step 4: Create a new tileset, I used the 2DBackgroundBlockAtlas texture
located in the 2DSideScroller content. Left all settings to default.
Step 5: Create a new tilemap, edit it and place some tiles in from our tileset created in the previous step.
Step 6: Place the new tilemap in the scene. I placed it at the same location as the player for quick testing.
Step 7: Set the material on the placed tilemap to MaskedLitSpriteMaterial.
Step 8: Add a light to the sceen. I used a directional light and pointed it towards the scene((Pitch=-45.000000,Yaw=-90.000000,Roll=0.000042)). I also gave it an extreme color so that I can clearly see the sprite and tilemap recieving light.
Step 9: Run the game in PIE and notice the lighting shows up on both the character and the tilemap. I used New Editor Window and Selected Viewport to confirm lighting works and it did for both the character and the tilemap.
Step10: Run the game using the Standalone Game option or the Launch button. I used both and confirmed that lighting works on the character, but not on the tilemap in these modes.