Issues with displacement map

Hello, I am currently experiencing issues exporting my displacement map from Zbrush. For some reason, details beyond a certain depth are not being included in the map. The problem is most visible at the seam of the nasal and frontal bone.

Let me know if you have any idea how to fix this, I can't seem to find a solution to it. I have tried changing any settings I can think to but details are still being lost. Thanks in advance for your help!