I just want to give you some information so you might be able to get on your way, unfortunately I have not got the experience to resolve this for you.
You are running into a gimbal lock issue due to the way that euler rotations (FRotator) are handled, the ranges for each of the values are -90 to 90. The solution to this is to use quaternions (FQuat). #gimbal #6DoF #quaternion Unreal Engine 4 Tutorial: 6DoF Fixing Gimbal Lock - YouTube is the tutorial I have found linked to several times to resolve this issue.
I hope it helps! Good luck!