Zbrush displacement map issue
Hi everybody!
I have some problems in Zbrush when creating displacement map on hard mesh surface.
Some white areas appear along the hard edges. Even if I didn’t sculpted anything.
For example on a simple cube with angle beveled to smooth the all thing.
At the beginning I was working on very low poly mesh with no bevel at all and I thought the problem was coming from the very sharp edges, but it’s not 
So here, let me explain my workflow in detail.
Here is a cube I’ve imported from maya.
Then, I’ve subdivided my mesh to sculpt it.
To finish I’ve created my displacement map.
As you can see every hard edges of my mesh are white and it would’t be anything because I didn’t sculpt anything on this edges.
When I apply my displacement map on a copy of my cube (virgin cube with just subdivisions here what it comes :
The sculpted area is good but all my hard edges are kind of inflated.
It’s been couple of days I try everything but each time, the result is the same.
Please help me, a big part of my project is in stand by till I or someone fix the problem.
I’ve found very few people with the same issue on the web, but the answers they get weren’t efficient .
Hope I’ve made myself clear ( I’m french).