I know this this was a known problem but has it been fixed yet ? I currently have this problem and can’t find any links to any solution.
I actually answered a question earlier today similar to the one you are asking. Just wanted to add a little note before I provide you with the links. The AnswerHub as well as the Forums are usually a good place to check to see if users are experiencing a similar issue, or even better, have found a fix for an issue you might be experiencing.
Deferred Decals Not Rendering with Direct Lighting
There are actually two posts that provide the same answer, but I figured I would give you both links just in case.
These posts should contain your resolution, but if you are still not seeing the decals please let me know.