Tried everything that’s been suggested just cant get this to work. My decals fade to transparent when they are in shadows. Is there something i am missing? I have set my project settings to Dbuffer decals, set Early Zpass to Opaque and masked meshes and ticked Movables in early z pass. I have also restarted the engine. Decals look great when they are in full light but as soon as they are on any object that is not in direct light then they go transparent.
Seriously someone help me with this and ill paypal you 20 bucks!
Hi, I faced the exact problem today. It appears this issue has workaround described here Decals not rendered without direct lighting? - Rendering - Unreal Engine Forums
In short you need to add 3 lines in BaseEngine.ini file locad in Engine Folder C:\Program Files\Unreal Engine\4.7\Engine\Config, NOT in project folder
put these 3 lines under [SystemSettings]
r.EarlyZPassMovable=1
r.EarlyZPass=2
r.DBuffer=1
Restart project
And now in Material Editor change Decal Blend Mode to something starting with DBuffer… DBufferTranslucentColor worked for me
[SystemSettings]
- r.EarlyZPassMovable=1
- r.EarlyZPass=2
- r.DBuffer=1
Thank you, I had figured this out late last night i was missing the blend mode, Your answer is spot on though and the most understandable i have seen, the blend mode picture will be a big help to people. So i will honor my 20 buck offer if you want it 
Thank you , it works to me and save my nervous system